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I 



THE GIFT OF 



1 






^r 



GEOLOGICAL SURVEY OF NEW JERSEY 



ANNUAL REPORT 



OF THS 



STATE Geologist 



For the Year J 906 



TBBNTON, M. J, 
liacOrelllBh ft Qnlgley, State Prlnten. 

190T 



It 



CONTENTS. 

Page. 

'^ Board of Managers, v 

Letter of Transmittai., vii 

Administrative Report, i.- Administration, 3; Topographic Work, 9; 
Geologic Investigations, 10 ; Awards at the Louisiana Exposition, 16. 

PART I. -The Fire- Resisting Qualities of Some New Jersey Building 

Stones, by W. E. McCourt, 17 

PART II. -The QIass-Sand Industry of New Jersey, by Henry B. Kiim- 

mel and R. B. Gage, 77 

^ PART ill.— The Origin and Relations of the Newark Rocks, by J. Vol- 

ney Lewis,. .^ 99 

The Newark (Triassic) Copper Ores of New Jersey, by J. 
* Volney Lewis, 131 

Properties of Trap Rocks for Road Construction, by J. 
: Volney Lewis, 165 

^ PART IV.— Notes on the Minhig Industry, by Henry B. Kiammel, 173 

List of Pubucations, 183 

Index, 189 



168543 



(iii) 



ILLUSTRATIONS. 



PLATES. 

Page. 

Plates I-XXIII. — Effects of fire tests on building stones, 32-76 

PtAT« XXIV. — Pumping plant—R. O. Bidwell's glass-sand pit, 85 

Plate XXV.— Washing plant—R. O. Bidwell's glass-sand pit, 86 

Plate XXVI. — Photomicrographs of glass sands, 87 

Plate XXVII. — Photomicrographs of glass sands, 88 

Plate XXVllt. — Map of the Newark (Triassic) System of New Jersey, 108 

Platb XXIX. — Map of borings showing buried trap, 118 

Plate XXX. — Map of location of copper mines, 135 

Plate XXXI. — Fig. i. Red shale, with disseminated lenticular calcite, 148 

Pig. 2. Shale with cavities filled with copper and 

chalcocite, , 148 

Plate XXXII. — Heave fault at old copper mine, Menlo Park, 154 

FIGURES. 

Figure i. — ^Areas occupied by the Newark System, 100 

Figure 2. — ^Topographic map of the southwestern part of the Watchung 

Mountains, iii 

Figure 3. — Geologic map of the southwestern part of the Watchung 

Mountains, 114 

Figure 4. — Cross section on line A-B, figure 3, 115 

Figure 5. — Map and section of the Griggstown Mine, 137 

Figure 6. — Map of Arlington, 140 

Figure 7. — Cross section at A, figure 6, Arlington, 140 

Figure 8. — Map and section of the Schuyler Copper Mine, 142 

Figure 9. — Diagram showing tests on trap rock as road metal, 169 



(iv) 



The Geological Survey of New Jersey* 



BOARD OF MANAGERS. 

His Excellency Edward C. Stokes, Governor and ex-oMcio Presi- 
dent of the Board, Trenton. 



Members at Large. 

Herbert M. Lloyd, Montclair, 1907 

Harrison Van Duyne, Newark, 1907 

S. Bayard Dod, Orange, 1908* 

John C. Smock, Trenton, 1908 

Thomas W. Synnott, Wenonah, 1909 

Alfred A. Woodhull, Princeton, 1909 

Emmor Roberts, Moorestown, 1910 

David E. Titsworth, Plainfield, 1911 

George G. Tennant, Jersey City, 1911 

Congressional Districts, 

I. Frederick R. Brace, Blackwood, 1911 

IT. P. Kennedy Reeves, Bridgeton, 1907 

in. M. D. Valentine, Woodbridge, 1909 

IV Washington A. Roebling, Trenton, 1908 

V. FREDERICK A. Canfield, Dover, 1910 

VI. George W. Wheeler, Hackensack, 1911 

VII. Wendell P. Garrison, Orange, i907t 

VIII. Joseph L. Munn, East Orange, 1909 

IX. Joseph D. Bedle, Jersey City, 1908 

X. Aaron S. Baldwin, Hoboken, 1910 

State Geologist, 
Henry B. Kummel. 



♦Died April 19th, 1907. 
t Died February 27th, 1907. 



(V) 



Trenton^ N. J., November 30, 1906. 
To His Excellency Edward C, Stokes, Governor of the State of 
New Jersey, and ex-oificio President of the Board of Man- 
agers of the Geological Survey: 

Sir — I have the honor to submit my Administrative Report 
upon the work of the Geological Survey for the year 1906. This 
will be followed by papers dealing with the Glass Sands, the 
Copper Deposits and other subjects, these with the Administra- 
tive Report comprising the Annual Report of the State Geologist. 
It has not been possible to complete these papers so as to submit 
them at this time, but the work on all of them is far advanced. I 
recommend that advance copies of the Administrative Report be 
printed for use of the Legislature and the printing of the whole 
report be deferred until these papers can be completed. In this 
,way the result of the investigations of this department may be 
placed most quickly before the citizens of the State. 

Yours respectfully, 

Henry B. KummEL, 

State Geologist, 



(vii) 



ADMINISTRATIVE REPORT. 



Administration, Organization, Publications, Distribution, 
Library, Collections, Correspondence.— Topography, 
Field Work, Office Work*— Geology, Peat, Building 
Stones, Trap Rock and Copffer Ores, Sands, Iron 
Ores, Mineral Waters, Artesian Wells, Pleistocene 
Stratigraphy, Paleozoic Stratigraphy, Paleontology^ 
Paleobotany* — Co-operation with the U. S* Geological 
Survey* — St* Louis Exposition Medals* 



I GEOI. 



J 

Administrative Rqx)rt* 



Henry B. Kummei., State Geoi/)Gist. 



A summary of the work of the Geological Survey during the 
fiscal year ending October 31, 1906, is set forth in the following 
pages of the Administrative Report, which, when published in 
its final form, will be accompanied by several papers giving in 
•detail the results of the work along particular lines. 

ADMINISTRATION. 

Organization, — In March, Mr. David E. Titsworth, of Plain- 
field, was appointed as a member at large on the Board of 
Managers to succeed Senator Ernest R. Ackerman, whose term 
Tiad expired and who declined re-appointment. Messrs. Ten- 
nant. Brace and Wheeler, whose terms also expired, were re- 
appointed for five years. 

During the year the following persons were employed upon 
the Survey, the majority of them at a per diem compensation : 

Henry B. Kiimmel, State Geologist. 

R. B. Gage, Chemist. 

Laura Lee, Clerk. 

Howard M. Poland, Office assistant. 



RoUin D. Salisbury, Surface Geology. 

G. N. Knapp, Surface Geology and Artesian Wells. 

Stuart Weller, Paleontology. 

E. W. Berry, Paleobotany. 

J. Volney I^ewis, Trap Rocks. 

C. W. Parmelee, Peat Testing. 

W. E. McCourt, Building Stones. 

(3) 



ANNUAL REPORT OF 

C. C. Vermeule, Topographer. 

P. D. Staats, Assistant Topographer. 

W. A. Coriell, Draughtsman. 

ly. M. Young, Topographic. assistant. 

Clarence Bruen, Topographic assistant. 

C. V. Coriell, Topographic assistant. 

J. B. McBride, Topographic assistant. 



Alma B. Roump, Stenographer. 
Anabelle Lesser, Stenographer. 
C. B. Hardenberg, Draughtsman. 
E. J. Davis, Clerk. 

Publications. — For various causes, in large part beyond the 
control of the Survey, the publication of the Annual Report of 
the State Geologist for 1905 (pp. 338 + X, plates XXX, figures 
in text 21) was delayed and the completed volume was not 
ready for distribution until the middle of October. Advance 
copies, however, of the administrative report and of two scien-^ 
tific papers were printed early in the year and were ready for 
the use of the Legislature. The completed volume contained 
the following papers : 



I 



Administrative Report, 24 pp. 

Changes Along the New Jersey Coast — Lewis M. Haupt, C. E., 70 pp. 

A Brief Sketch of Fossil Plants — Edward W. Berry, 38 pp. 

The Flora of the Cliff wood Clays— Edward W. Berry, 38 pp- 

The Chemical Composition of the White Crystalline Limestones of 
Sussex and Warren Counties — Henry B. Kiimmel, with analyses 

by R. B. Gage (with map) , 16 pp^ 

Lake Passaic Considered as a Storage Reservoir — C. C. Vermeule 

(with map), 30 pp. 

A Report on the Peat Deposits of Northern Kew Jersey — C. W. Par- 
melee and W. E. McCourt (with map), 86 pp. 

The Mining Industry — Henry B. Kummel, 12 pp. 

Three new Atlas sheets, Pluckemin, SomerviUe and New 
Brunswick, on the large scale (2,000 feet per inch) were pub- 
lished in May, and at once placed on sale. Twenty-four sh^s 
on this scale are now completed and are being distributed as 



THE STATE GEOLOGIST. 5 

rapidly as orders are received. One hundred and two sheets on 
this scale are necessary to cover the entire State, but the sheets 
already published cover the more populous centers. There is 
practically no demand for sheets of this character covering the 
strictly agricultural and woodland areas, for which the maps of 
the earlier series on the smaller scale amply suffice. It is doubt- 
ful therefore whether it will be advisable to issue in the near 
future many more sheets on the larger scale. 

One sheet, No. 21, on the one-inch per mile scale, was re- 
issued in August, after extensive revision of the cultural fea- 
tures. This sheet, covering northern Warren and western Sus- 
sex counties, replaces the old Sheet No. i, although it does not 
•cover exactly the same limits. 

Distribution. — ^The demand for the maps and reports issued by 
the Survey is, to a certain extent, an index of the degree to which 
the work of the department commends itself to the people. This 
is particularly the case with respect to the maps which are not 
"distributed gratuitously but are sold at 25 cents per sheet. Judged 
"by this test the work is approved, since the map sales during 1966 
numbered 4,581 sheets as against 3,187 for 1905 and 2,236 for 
1904. It is true that the number of different sheets on sale has 
increased from 37 in 1904 to 43 in 1906, but the average number 
of copies sold per sheet was 60 in 1904, 80 in 1905 and 107 in 
1906. There were 653 separate orders, making an average of 7 
•sheets to each order. During the past year the sales of both the 
one-inch maps and the large-scale sheets have increased about 50 
per cent., and about 700 more copies of the latter were sold than 
of the former. The unexpected increase in the demand for these 
maps during the last two years has exhausted the editions of 
many of the older sheets, and necessitated the printing of new 
•editions. The time seemed opportune for extensive revision, so 
as to bring the new editions down to date. This has been done, 
although in some instances it has delayed the publication of the 
maps and increased very considerably the proportion of Survey 
funds needed for this work, but it has been necessary in order 
to maintain the high standard of excellence for our maps estab- 
lished in previous years. 



6 ANNUAL REPORT OF 

The total number of reports sent out during the year is set 
forth in the following table, which shows a considerable falling 
off over the last two years. The reason for this is found in the 
fact that three reports — ^two annuals and Volume VI, the Clay 
Report— were issued in 1904 and 1905. Not only were these 
three reports distributed to a long mailing list, but their distribu- 
tion, particularly that of Volume VI, stimulated a demand for 
the previous reports. The Annual for 1905 was sent out so late 
in 1906 that the demand for back reports, which is usually^ 
aroused by a new volume, has not yet been felt. 

Below is shown in tabular form the distribution of reports and 
maps for 1905 and 1906: 

jgos. 1906. 

Annual Report for 1905, 3,237 copies 

1904, 5»279 copies 147 " 

1903, 165 " 72 " 



it It 

tt It 

It tt 

tt tt 

*t tt 



1902, 71 " 43 " 



1901, 60 " 42 " 

1900, 77 " 67 " 

" Reports between 1883- 1899, 775 " 570 " 

Final Reports, Vol. II, 238 " 99 "^ 

Vol. Ill, 151 " 81 '^ 

Vol. IV, 136 " 85 "- 

Vol. V, 175 " 89 '^ 

Vol. VI, 985 " 177 '*- 

Other Reports, 126 " 107 **^ 



(( 


tt 


(( 


tt 


(( 


tt 


tt 


tt 



Total Reports, 6,238 " 4,716 

Map sheets — 

Scale I inch per mile — 19 sheets, 1,245 1,974 

Scale 2,000 feet per inch— 24 sheets, 1,942 2,607 



Total map sheets, 3,187 4,581 

Library, — The accessions to the library of the Survey during" 
the year were 55 bound volumes, 119 unbound volumes, 109 
pamphlets, 88 maps. The bulk of these were obtained by ex- 
change. 

Collections, — The geological collections of the Survey have 
not been materially increased during the year, but much has been 
done towards making the material on hand more accessible for 



THE STATE GEOLOGIST. 7 

reference. The mineral and rock specimens have been numbered, 
and the labels entered in a permanent accession book. Index 
cards have also been prepared for many of the specimens. Some 
work has been done upon the paleontological material, but it will 
be some time before all collections are properly classified. When 
the work is completed there will be a list of all specimens arranged 
numerically in a book, and a card index arranged by subjects 
and localities. A permanent label number in paint has been placed 
on each specimen, and there is no chance of the specimen becom- 
ing valueless by reason of its label being lost. Mr. Poland has 
performed this work under my direction as he has had time from 
other duties. 

There are still on hand four of the mineral collections prepared 
for the use of schools of the State which are available for distri- 
bution to any school, upon payment of $25.00 to cover the cost 
of preparation, labelling and packing. 

Correspondence, — Many letters are received containing in- 
quiries of various sorts. These have a wide range, varying from 
a request for the elevation above sea level of some point in the 
State, or the area of some lake, questions which can be readily 
answered by reference to the publications of the Survey, to more 
complicated requests for advice in reference to underground 
water supplies, the occurrence and chemical composition of glass 
sands, peat, pure limestone and a host of other subjects. In many 
instances the inquiry can be answered by sending one of the 
printed reports ; in other cases it is necessary to spend considerable 
time in looking up the necessary data, comparing the evidence, 
and writing a letter in reply. It is the policy of the Survey to 
reply to all communications as fully as possible and to furnish 
the desired information whenever possible, in the belief that such 
a course best brings our work into close touch with the people. 
No charge is made for information of this chairacter. Not a few 
of the inquiries come from, other States, and, in some cases at 
least, the information furnished is believed to have resulted in 
the establishment of new industries here. 

Occasionally the Survey is in receipt of letters asking for in- 
formation regarding New Jersey mining propositions which are 
being "promoted" on the market. It is a matter of extreme 



8 ANNUAL REPORT OF 

difficulty to reply to these in such a way as to be absolutely fair 
to all parties. It is no part of the work of the Survey to offer 
advice to prospective investors (either for or against a proposi- 
tion), but it is a proper function to set forth through its reports, 
and in response to inquiries, geological facts known and of 
record which bear upon the- case. Ordinarily, it is believed that 
our duty to the investing public is done when such a reply has 
been made to a direct inquiry. 

It seems necessary, however, to call attention here to the 
recent prospectus of a company promoting a zinc-mining proposi- 
tion near Franklin Furnace, adjoining the well-known mines of 
the New Jersey Zinc Company, for the reason that the work of 
the State Geologist is cited in such a way as to make it appear 
that this department endorses the claims set forth in the cir- 
c'ular. The Geological Survey most emphatically does ,not do 
this. There are no facts in its possession which warrant the 
claim that zinc ore in commercial quantities occurs anywhere 
in the State except in the two famous ore-bodies at Franklin 
Furnace and Stirling Hill, respectively. Thousands of dol- 
lars have been spent in recent years in diamond drilling on 
neighboring properties in the vicinity of these ore-bodies with 
negative results so far as this department knows. In all future 
prospecting by this means, it should be clearly recognized by 
those whose money is invested, that exploration with a diamond 
drill is very expensive, costing several dollars per foot, that the 
expenditure of $20,000 may be necessary to test properly a single 
hole, and that the chances of locating a workable body of zinc 
ore by one or two holes put down in the crystalline limestone even 
in the most favorable spot are very remote. 

Maps published in the Annual Reports of the State Geologist 
for 1890 and for 1905 show that the property of this company is 
not underlain entirely by the white limestone, as is claimed, but 
in large part by the blue limestone which is highly magnesian in 
character and utterly valueless for the purposes of Portland ce- 
ment manufacture. White crystalline limestone, containing very 
little magnesia, does, however, occur on their property but much 
less extensively than the other. 

The prospectus quotes parts of a report on this property writ- 
ten in 1903 by Mr. Frank L. Nason, who is referred to as if he 



THE STATE GEOLOGIST. 9 

were a member of the State Survey when he made the report, 
whereas he severed his connection with the Survey in 1 890. This 
abridged report misrepresents facts and tends to mislead, but in 
justice to Mr. Nason, who was an active and painstaking worker 
on the Survey for a number of years, it should be stated that the 
report as written by him and the report as pubHshed in the pros- 
pectus, lead to very different conclusions. 

EditoriaL — In addition to preparing parts of the Annual Re- 
port for 1905, the manuscript of the balance was read and edited 
by the State Geologist, and the entire report read both in galley 
and page proof. 

TOPOGRAPHIC WORK., 

Mr. C. C. Vermeule has continued to direct the topographic 
work with P. D. Staats, W. A. Coriell, L. M. Young, Clarence 
Bruen, C. V. Coriell and J. B. McBride as assistants for varying 
periods. 

Field Work, — Early in the year the revision of Sheet 21 was 
commenced, and owing to the mildness of the weather it was 
possible to continue the field work even during January and 
February, covering 270 square miles. Some field work was found 
to be necessary in connection with the proof sheets of the Pluck- 
emin, Somerville, and New Brunswick sheets. Owing to altera- 
tions at the County Buildings at Somerville, two bench marks of 
the Survey were in danger of destruction. Temporary bench 
marks were established, and on the completion of the new County 
Buildings they will be transferred and made permanent. It was 
not possible last year to complete the surveys in reference to the 
proposed lake in the upper Passaic Valley, described at length 
in the Report for 1905, so that considerable field work was neces- 
sary during the early part of this year. Delay in publishing *the 
Report for 1905, however, made it possible to include the results 
of these studies in that report. 

Office Work, — Drawings for photolithographing the Pluck- 
emin, Somerville and New Brunswick sheets were completed, and 
the changes on Sheet 21 were transcribed and copy made ready 
for the engraver. The work of preparing a borough and town- 



lo ANNUAL REPORT OF 

ship map to be printed in color was completed and copy sent to 
the lithographer. Drawings were made of the Lake Passaic 
map. In addition to this, the proof of seven maps was read and 
corrected. ^ 

The growing popularity of the Survey maps, as evidenced by 
the increased sales, has already been alluded to. A new State 
Map, on a scale of 5 miles to i inch, and corrected so as to show 
the boundaries of all boroughs, townships, cities and counties,, 
as they existed after the adjournment of the last Legislature, has 
been prepared and will be published soon. It will be printed in 
colors to make the political boundaries more prominent. The 
demand for it will probably be large. It will be .Sheet No. 38,. 
and will be sold at the regular price of 25 cents. 



GKOI.OGIC INVESTIGATIONS. 

Peat. — The laboratory determinations necessary to complete 
the report upon the peat deposits kept Mr. Parmelee busy during- 
the winter and spring. His conclusions were published as part 
of the Annual Report for 1905, it being deemed better to delay 
the completion of that volume slightly, so as to ensure prompt 
publication of these results. 

Building Stones, — Mr. McCourt, in continuation of the experi- 
ments commenced a year ago, has made a few more tests upon the 
btfilding stones of the State, to determine their fire-resisting qual- 
ities. The discussion of his experiments, with illustrations show- 
ing the effect of sharp changes of temperature upon his specimens,. 
will be published as a paper to accompany this report. 

Trap Rock and Copper Sttidies. — Mr. J. Volney Lewis has 
continued his investigations of the petrography of the trap rocks,, 
and the questions which bear upon the origin of the copper ores 
so commonly found in the shales in close proximity to them. 
The rocks of the Newark formation, including the traps, were 
discussed in some detail in the Annual Reports for 1896 and 
1897, but certain phases of the subject were not touched upon 
at all, and others are shown by further study to be susceptible 
of a different interpretation. In the last few years there has been 



THE STATE GEOLOGIST. ii 

a marked change in the opinion of geologists regarding the 
origin of extensive formations of shale and sandstone, formerly 
accepted without question as of estuarine or lacustrine origin, 
but now believed more probably to be fluviatile deposits. For 
som,e time the writer has felt that his discussion of this subject 
in the Annual Repart for 1897 was inadequate, and should be 
revised, and for this reason he is pleased to direct attention to the 
alternative view outlined by Mr. Lewis in his report. 

The correlation with each other of the various trap masses as 
developed by Mr. Lewis is highly suggestive. Although it can 
not be claimed that it rests upon so firm a basis of ascertained 
facts, as do many of the other conclusions regarding these rocks, 
nevertheless there is nothing inherently improbable in his con- 
clusions, and much can be said in their favor. They can be ac- 
cepted, therefore, as a good working hypothesis to be held until 
definitely disproved. 

The explanation given by the writer in the* Annual Report for 
1897, for the double crest of Second Mountain with the beds of 
shale in the valley, was never wholly satisfactory and was offered 
with considerable hesitation, and a full comprehension of the in- 
herent difficulties. The alternative hypothesis proposed by Mn 
Lewis seems less beset with difficulties and it should probably re- 
place the earlier view. 

Regarding the origin of the copper ores, the view put forward 
by Mr. Lewis that they are deposits from ascending magmatic 
waters expelled from the great intrusive mass, whose separated 
portions now outcrop as the Palisades, Rocky Hill, Sourland 
Mountain, etc., varies distinctly from the view suggested by Dr. 
W. H. Weed,* respecting the ores under the trap ridge of the 
First Watchung Mountain. Owing to this differei!ce of opinion, 
the facts set forth by Mr. Lewis in support of his hypothesis are 
of more than ordinary interest. 

Another feature of interest in his report will be found in the 
tests of the resisting qualities of the trap as determined by a series 
of experiments carried out by the co-operation of the Director 
of the Office of Public Roads, Department of Agriculture, at 



* Annual Report of the State Geologist for 1902, p. 137. 



12 ANNUAL REPORT OF 

Washington, D. C. Inasmuch as the trap rocks are used very 
extensively for road metal, these tests of their wearing qualities 
should prove of value when considered with regard to the results 
already shown by actual usage. Mr. Lewis' discussion of the 
petrographic features of the trap rocks will be considered in a 
subsequent report. 

Sands, — ^A brief paper has been prepared upon the glass sands 
of the State. Chemical analyses of the New Jersey sands show 
that they contain more iron than do the Pennsylvania sands 
with which they come in competition, with the result that the 
latter bring much better prices per ton at the glass factories. 

The methods of washing the sands practiced at the pits re- 
move the fine clay and silt which remain suspended in the water, 
and also the grains and pebbles too large to pass a 30-mesh 
sieve. Mineralogical examination of the samples of washed glass 
sands collected by the Survey shows that practically all the iron 
and titanium shown by chemical analyses is contained in small 
grains of rutile, ilmenite, sphene and leucoxene (?). As Mr. 
Gage points out in his report, if the iron-bearing minerals can 
be removed by improved methods of washing, by magnetic sep- 
aration, sieving, or any method which in its practical operation 
is not too expensive, a grade of glass sand equal to or even 
superior to the best Pennsylvania sand can readily be obtained. 
When the difference in price between the Pennsylvania and the 
New Jersey sand^as at present marketed is considered, the im- 
portance of this point to local glass-sand miners is apparent. 

Iron Ores. — During the year. Dr. W. S. Bayley, in the time 
available from his other work, has continued his compilation of 
data regarding the iron mines of the State. It is expected that 
it will be cornpleted during the present year and be published 
•early in 1908. In this connection a detailed map of the Hibemia 
mines is being prepared on a large scale. The report will be ac- 
companied by other maps, both of the surface and of the under- 
ground workings of various mines. 

Mineral Waters. — Late in the year Mr. Gage visited the min- 
eral springs of the State, the waters of which are placed on the 
market and have a more or less extended table use. Samples 
were taken and mineral analyses will be made in the near future. 



THE STATE GEOLOGIST. 13 

The use of bottled spring water for drinking is increasing rap- 
idly, as the surface supplies become open to suspicion through 
contamination by sewage. 

Artesian Wells. — ^The underground water supplies of the State 
have long been a subject for study by the Survey. In many of 
the Annual Reports, notably those from 1890 to 1903, records 
of many artesian and other deep wells were published and some 
attempts made to correlate water horizons. In 1904, Mr. G. N. 
Knapp began the work of revising these records and correlating 
the many samples of borings which the Survey had obtained. 
This work was at first undertaken in co-operation with the Hydro- 
graphic Division of the U. S. Geological Survey, and the ex- 
pense was defrayed by them, in consideration of the initial work 
done by the State Survey in collecting the data. For various 
reasons Mr. Knapp has been delayed in the completion of the 
work, and the U. S. Survey was compelled to give up further 
particii>ation in it. Since August ist the work has been carried 
on at the expense of the State Survey, and the report will be 
completed by the end of December. 

It is proper here to state that the U. S. Geological Survey in 
ceasing to co-operate further in this investigation freely waived 
all claims to any part of the results already reached. 

Stratigraphy. Pleistocene. — The interpretation and mapping 
of the surface sands and gravels of southern New Jersey have 
engaged the attention of the State S^urvey under Mr. Salisbury 
and his assistants portions of each year since 1892. Similar de- 
posits in States further south were studied by other workers, and 
results were reached by them which did not harmonize with those 
put forth by this department. When the southern interpretation 
was carried northward and applied to deposits on the west side of 
the Delaware, and then extended into New Jersey, the differences 
in view were emphasized and tne necessity for a modification in 
some direction was apparent. This was thie more necessary since 
the U. S. Geological Survey is publishing a geological atlas of the 
whole country, and is working in co-operation with the New 
Jersey Survey as well as with some other State surveys in their 
respective States. 



14 ANNUAL REPORT OF 

In June a field conference was held in New Jersey) in which 
Messrs. C. W. Hayes and Benjamin L. Miller, of the U. S. 
Geological Survey, and R. D. Salisbury and G. N. Knapp, of the 
New Jersey Survey, together with the State Geologist, took part. 
The deposits on both sides of the Delaware river were examined 
with maps in hand which represented the diverse views. The 
resiilt of the conference was the acceptance of the interpretation 
and the mapping urged by the workers on the New Jersey Survey, 
and the decision to bring the Pennsylvania work into harmony 
with it. Some changes in the details of our mapping, in part 
because of clerical .errors in transcribing the maps, were sug- 
gested and agreed to, but the subdivisions advocated and the 
interpretation put upon the deposits by the New Jersey Stirvey 
were accepted as correct by Mr. Hayes for the National Survey. 
This decision removes one of the causes of the long delay in 
publishing the geologic atlases of the southern part of the State. 

Upon the termination of this conference, Mr. Knapp took up 
and by the end of July completed his maps and manuscript upon 
these formations. The final report will now be prepared for 
publication by Mr. Salisbury, and will be a companion volume to 
his Report upon the Glacial Geology, which was published in 
1902 as Volume V. 

Stratigraphy. Paleozoic. — ^The structural relations of the 
limestones and shales of Warren county present some interesting 
features which were the subject of careful examination during a 
few days in July by the State Geologist. The normal Paleozoic 
succession in the Kittatinny valley is as follows, from the top 
downward : 

Hudson shales and slates, thickness great. 

Trenton limestones (essentially non-magnesian), 100-200 feet. 

Kittatinny limestone (mostly magnesian), thickness probably 
about 3,000 feet. 

Hardyston quartzite, 20-150 feet. 

This succession can usually be traced in making a cross-section 
from the crystalline Highlands to the Kittatinny Mountain, which 
is com.posed of the Shawangunk conglomerate (more frequently 
called Oneida conglomerate, but recently determined by the New 
York Survey to be Salina in age). In the vicinity of Hope, 



THE STATE GEOLOGIST. 15 

Johnsonburg and the northern end of Jenny Jump Mountain, 
however, the structure is very compHcated and the relations of 
the rocks can be determined with difficulty. Areas of the Kitta- 
tinny limestone of varying size occur surrounded entirely by the 
Hudson slate, while the Trenton Hmestone, which should occur 
between them, is entirely absent. That these are not simply 
eroded anticlinal folds showing the older rocks in the center 
surrounded by younger beds is shown both by the absence of the 
Trenton formation and by the inclination of the strata which do 
not possess the anticlinal structure. That the region has been 
greatly faulted is evident even upon cursory examination, but 
data to determine the exact nature and position of the fault 
planes, as well as the direction and amount of thrust, are not easy 
to find. It seems demonstrable, however, that in the folding 
which occurred in this region the limestone was thrust horizon- 
tally over the shale from southeast to northwest for a consider- 
able distance. Later in the folding the thrust plane itself became 
somewhat folded, being depressed in troughs and rising in broad 
gentle arches. Subsequent erosion has removed hundreds of 
feet of sediment. Where the thrust plane was depressed so as to 
be still below the limit to which erosion has now progressed, that 
is below the present surface, the overthrust beds of limestone are 
found upon the slate. Where the thrust plane was slightly arched 
the limestones have been removed, and the present surface is in 
the shales below the thrust. 

This explanation makes clear also the presence of several small 
areas of crystalline rocks, the occurrence of which within the 
limestone and slate areas far removed from the gfreat mass of 
gneisses and gfranites, is not readily explained on other hypoth- 
eses. They are not intrusives in the sedimentary rocks, nor are 
they normal exposures of the underlying crystallines revealed by 
deep erosion. On the contrary, like the limestone areas above re- 
ferred to, they are remnants of the basal rocks which in the fold- 
ing were thrust horizontally over and upon the much later sedi- 
ments. 

Paleontology, — ^Dr. Weller has almost completed his studies of 
the fossils found in the sands, clays and marls of the Cretaceous 
strata, and the report will soon be ready for publication. It will 



i6 ANNUAL REPORT OF STATE GEOLOGIST. 

add miich to our knowledge of the life of this period, and will be 
a valuable contribution to the Paleontology of New Jersey. Ow- 
ing to its purely technical character, only a small edition will be 
printed, and its distribution will be limited. 

Paleobotany. — ^A small allotment was made Mr. E. W. Berry 
in connection with like sums from the Maryland Survey and the 
National Survey to enable him to continue his studies of the 
fossil plants of the Coastal Plain, the money contributed by this 
department being spent only in New Jersey. 

Co-operation with the U. S. Geological Survey, — As already 
indicated, a field conference has been held with representatives of 
the U. S. Geological Survey, as provided by the agreement made 
in 1904*, at which the interpretation of the non-glacial Pleisto- 
cene deposits of the southern counties, urged by Messrs. Salis- 
bury and Knapp, of the State Survey, were accepted for use in 
the geologic atlas. This, of course, involved the rejection of the 
opposing view, and will necessitate, the re-mapping by the U. S- 
geologists of the same formations on the Pennsylvania side of the 
Delaware River to bring them into accord with the New Jersey 
work. It is hoped that, as soon as this is done, the maps of this 
region can be issued without further delay. 

In June the manuscript descriptive of the Paleozoic sediments 
on the Franklin Furnace quadrangle was prepared and sent to 
Washington. The State's share of this work has now been com- 
pleted. The manuscript of three other quadrangles is in various 
stages of preparation, but it is difficult to say when the conv 
pleted maps will be issued. 

Awards at the Louisiana Purchase Exposition. — ^During the 
year the Geological Survey received the medals indicative of the 
awards made to it for its display at the St. Louis Exposition in 
1904. A grand prize was received for the maps and models; 
four gold medals for the exhibits of clays, rcfcks and minerals, 
fossil restorations and collective exhibit respectively, and a silver 
medal for a museum petrographic microscope. The medals are 
all of bronze metal, but the various grades are distinguished by 
their shape and by slight differences in design. 



♦Annual Report of the State Geologist for 1904, p. 15. 



PART L 



The Firc-Rcsisting Qualities of Some 
New Jersey Building Stones* 



By W. E. McCOURT. 



2 GEOL (17) 



The Fire-Resisting Qualities of Some New 

Jersey Building Stones. 



BY W. E. MCCOURT. 



OUTLINE. 



Introduction. 

Earlier investigations. 

Observations in burned buildings. 

Method of making the fire tests. 

Samples tested. 

General summary of results. 

Granites and Gneisses. 

Diabases. 

Sandstones. 

Limestones. 

Argillite. 
Detailed statement of experiments, with illustrations. 

INTRODUCTION. 

In order to determine the durability of a building stone a 
number of tests are performed on it. Certain tests are, in cer- 
tain cases, more important than others, though all are desira- 
ble in order to get at the relative merits of building stones. 
There is one test which has often been neglected, and this is the 
effect of extreme heat. This is of much importance in some 
cases, especially when the stone is to be used in a location where 
a conflagration is apt to occur. 

Accordingly, a number of samples of New Jersey stones were 
collected by the writer during the summers of 1904 and 1905, 
under the direction of the State Geologist, and these were tested 
in the Geological Laboratory of Cornell University, in connec- 
tion with work for an advanced degree. The object of this 

(19) 



20 THE STATE GEOLOGIST. 

investigation was to ascertain the relative ability of the various 
stones to withstand extremie heat, and to determine, as far as 
possible, the criteria which control the refractive ability. 

The writer wishes to express his appreciation of the courtesies 
extended to him by the various laborers, superintendents and 
owners at the quarries visited. Thanks are due to many, but 
special mention is due Mr. W. J. Ledger, of the S. B. Twinning 
Co., Mr. Merriman, resident engineer at the Boonton Dam, Mr. 
George Sweezy, of the Federal Hill Granite Co. and Mr. Her- 
bert K. Salmon, of the North Jersey Stone Co. To Dr. A. C. 
Gill, of Cornell University, acknowledgment is due for help 
in the petrographic descriptions of the samples, and to Dr. Hein- 
rich Ries, of Cornell University, for general criticism of the 
entire work. Most of the photographs for this paper were- 
taken by Mr. G. F. Morgan, of Ithaca. 

EARUER INVESTIGATIONS. 

Investigations of the refractoriness of building stones are 
comparatively few. Cutting^ was the first to perform any ex- 
tensive tests and from his results he came to the conclusion that 
the various stones for building purposes withstand extreme heat 
in the following order : Marble, limestone, sandstone, and gran- 
ite, but all were injured to some extent. 

Buckley^ carried on a series of tests on Wisconsin and Mis- 
souri building stones, and came to the conclusion that a stone 
with a simple mineralogical composition, and a uniform texture 
has the greatest capacity to withstand high heat. According to 
him, limestones, up to the point of calcination, acted best of all 
the stones, but beyond that point they flaked off at the comers. 
The grajiites all cracked, though in varying degrees, the coarser 
grained ones suffering the greatest injury, while the sandstone 
showed little outward evidence of damage, but most of them 
could be crumbled in the hand. 



* Weekly Underwriter, XXIII, 42, 1880. Ibid XXII, 257, 287, 304, 1880. 

* Wis. Geol. & Nat. Hist. Sur. Bull. IV, 7i & 385, 1898. Mo. Bur. of Geo!. 
& Mines, II, 2nd series 50, 1904. 



FIRE TESTS ON BUILDING STONES. 21 

The consensus of opinion seems to be that granites are the least 
refractory of the building stones. The limestones and marble 
calcine and flake off at a high heat, while some of the sand- 
stones stand up well, and others are reduced to sand. 



OBSERVATIONS IN BURNED BUII.DINGS. 

The literature of the effect of fires on the various kinds of 
stone was studied to see if any facts might be deduced, but we 
cannot safely draw any definite conclusions, since the actual con- 
ditions in a fire are varied, and there have never been any de- 
tailed or accurate observations made at the time of the confla- 
gration. However, it is of interest to note that in an intense 
fire all stones are injured to some extent, especially where the 
stonework is thin or exposed. Until accurate observations of 
the different conditions of exposure, amount of heat, etc., in a 
conflagration are made, we cannot safely draw any conclusions 
from this source as to the relative refractoriness of the different 
building stones. 

METHOD O^ MAKING ]?IRE TESTS. 

In the tests to be described 3-inch cubes were used. All 
Other investigators have employed smaller cubes, but these do 
not give so accurate results as those of a larger dimension. 
When a larger cube is heated, the heat penetrates only a slight 
distance into the body, while the interior may remain compara- 
tively cold. Upon cooling there are set up differential stresses 
which would not be caused in a small sample of the stone. 
Tests have been made on larger and smaller cubes of the same 
kind of stone, and invariably the small pieces stood the heat 
much better than the larger cube. Naturally, then, the large 
cube should always be used, as this approximates more closely 
conditions which prevail in buildings. 

As far as possible six tests were made on the stone from each 
locality. Four of these tests were made in a Seger gas-furnace, 
which allowed the cube to be gradually and evenly heated. In 



22 THE STATE GEOLOGIST. 

the cover of the ■ furnace an opening was cut large enough to 
admit the specimen, to which a wire had been fastened in order 
to facihtate handling. Two flame tests were carried on, and for 
these an ordinary blast lamp was made use of. 

In the furnace tests one sample was heated at a time. After 
the cube had been placed in the furnace the heat, measured by a 
thermo-electric pyrometer, was applied gradually for half an 
hour untif a temperature of 550° C. (i022°P) was reached. 
This degree of heat was maintained for half an hour, and at the 
end of that time the sample was removed from the furnace and 
allowed to cool in the air. The second cube was heated like the 
first, but this was suddenly cooled by the application of a strong 
stream of water. The third and fourth samples were heated 
to 850"^ C. (1562°), kept at that temperature for half an hour 
and then cooled, one slowly and the other suddenly, as the tests 
at 550° C. 

In the first flame test the cube was so placed as to be enveloped 
on three sides by a steady but not strong gas blast. The flame 
was allowed to play on the cube for 10 minutes, then the sample 
was allowed to cool for five minutes, at the end of which time 
the flame was again applied for 10 minutes and the cube was 
again allowed to cool. The second flame test was carried 011 
somewhat similarly to the first test, but in this case a strong 
stream of water was applied, along with the flame, for five min- 
utes after the cube has been subjected to the flame alone for 10 
minutes. The water was turned off and the flame allowed to 
act on the cube for another five minutes, after which, for five 
minutes more, the flame and water together acted on the sample. 



sampi,e:s tested. 



Samples tested were obtained from the following localities : 



FIRE TESTS ON BUILDING STONES. 



23 



LOCALITY. 



COUNTY. 



COMPANY. 



Plate 
Reference. 



GRANITES AND GNEISSES. 



German Valley, i mile 
northwest, 

Cranberry Lake, 2 miles 
south, 

Cranberry Lake, 

Montville, i mile north,. 

Pompton Junction, 

Dover, 

Mt. Arlington 

Waterloo, 

Hibernia, 3 miles north- 
west, 

Morristown, i mile west, 



Plainfield, i mile west,.. 
Lambertville, 

Wilburtha, 

Stockton, 

Raven Rock 

Martinsville, Yi mile 

south, 

Pleasantdale, 

Avondale, 



Morris, 

Sussex, 
Sussex, 
Morris, 

Passaic, 
Morris, 
Morris, 
Morris, 

Morris, 
Morris, 



Lyman Kice, 



North Jersey Stone Co.,. 
Panther Hill Granite Co., 
Jersey City Water Sup- 
ply Co., 

Federal Hill Granite Co., 

Thomas Fanning, 

North Jersey Stone Co.,. 
North Jersey Stone Co.,. 



P. Lubey, 

DIABASES. 

Somerset, . . F. W. Wilson & C6., . . . 
Hunterdon,. B. M. & J. S. Shanley, . . 

SANDSTONES. 



Avondale, 



North Arlington, 

Closter, 2 miles east, 



Frankim Furnace, 

Newton, 

Phillipsburg, 



Mercer 

Hunterdon, . 
Hunterdon, . 

Somerset, .. 

Essex, 

Essex, 



Essex, . 

Hudson, 
Bergen, 



De Graves Bros., 

S. B. Twinning Co., 

Stockton Stone Co., 

W. E. Bartle, 

F. W. Shrump, 

Belleville Quarry and 

Stone Co., 

Belleville Quarry and 

Stone Co., 

Geo. Bayliss, 

J. Gamble & Son, 



LIMESTONES. 



Sussex, 

Sussex, 

Warren, . . . 



Nicol Limestone Co., 

0*Donnel & McManiman, 



ARGIIXITE ROCK. 

Princeton, i mile north,. ( Mercer I Margerum Bros., 



I. 

n. 

H. 

HL 
IV. 
V. 
VL 

vn. 

VHL 
IX. 



X. 
XI. 



xn. 
xin. 

XIV. 

XV. 
XVI. 

XVII. 

XVII. 

XVIII. 

XIX. 



XX. 

XXI. 
XXIL 



XXIIL 



RESULTS OF THE TESTS. 



General Summary. — The crystallines, at a temperature of 550° 
C. (1022° F.) were not greatly affected, and the cracks which 
were developed were but slight. The gneisses, as a rule, cracked 
parallel to the banding, and as a general thing it is fairly safe 



24 THE STATE GEOLOGIST. 

to say that a gneiss will be more damaged than a crystalline 
rock of the same texture and similar mineralogical composition 
without the banding. The sample of clay rock from Princeton 
acted badly. Clay rocks usually suffer much damage in a fire. 
Well known examples of this are seen in the splintering and 
shivering into fragments of the roofing slates and those used on 
staircases. The sandstones, as a whole, resisted well at the lower 
temperature, while the limestones seem to have suffered the least 
. injury of all the stones tested at 550°. 

The degree of heat which is reached in a conflagration un- 
doubtedly exceeds 550° C, but outside of the severe part of the 
fire there would be buildings subjected to a temperature of 
550° or thereabouts. The stones in such buildings would prob- 
ably suffer very little injury. Limestones would act best, pro- 
vided the point of calcination had not been reached. Sand- 
stones would follow limestones in their ability to resist the 
damage from the heating. To be sure, this series of tests has 
shown that some of these New Jersey samples cracked, but the 
cracks are slight, and in most cases parallel to the planes of bed- 
ding. This damage would not materially affect the stability of 
the structure if the stones had been properly set on their beds. 
Fine-grained crystallines would follow sandstones, and last would 
come the coarser crystallines. 

When we approach a heat equal to 850° C. (1562° P.) we ap- 
proximate fairly well the probable degree of heat which is 
reached in a conflagration. In this series of experiments the 
crystallines, as a class, acted badly, though some samples gave 
better results. In the case of the igneous rocks the main factor 
controlling the refractoriness seems to be the texture. The finer,- 
grained varieties act much better than the coarser ones. In the 
stones of the fine texture the cracks are small and quite regular, 
with a tendency to split off the corners, whereas in the stones ot 
coarser texture the cracks are irregular and open, and in some 
cases they were so bad as to cause the cube to crumble. The 
gneisses would suffer great injury and the amount of damage 
would be largely controlled by variations in texture and the 
amount and style of banding. Those stones in which there are 
seams of coarser material will crack considerably more than the 



FIRE TESTS ON BUILDING STONES. 25 

even-grained varieties, and the much banded gneiss will tend to 
split more readily, especially in a direction parallel to the banding. 

Naturally the sandstones vary somewhat in their ability to 
withstand the effect of this extreme heat. Here the controlling 
factors seemed to be texture, composition, kind of cementing 
material and manner of cementation. The coarser-grained 
stones and those made up of various mineral constituents suffered 
worse than the finer-grained and more simple ones. It is to be 
inferred that a compact stone will suffer less than one in which 
there are a number of pore spaces. The greater the percentage 
of porosity, in general, the greater will be the damage. A very 
porous stone will be reduced to sand, while a dense one will 
behave quite creditably. A coarse stone will crack irregularly, 
while a finer-grained one will split more regularly and in most 
cases in a direction parallel to the lamination planes. A sand- 
stone which has a cement of limonite or one in which there is a 
large percentage of clay will crack more readily than one in 
which silica or calcite bind the grains together, for the reason 
that the water is driven off from. the clay and limonite, and as a 
consequence greater stresses are set up in the stone. 

The limestones, at the higher temperature, because of the fact 
that the calcination point has been reached, flaked and in some 
cases went to pieces. A pure limestone suffered greater injury 
than the impure or dolomitic samples. 

The results of the flame tests cannot be considered as indicative 
of the probable effect of a fire on the body of the stone in a 
structure, but, more correctly, may be considered as a probable 
indication of the effect on thin edges of stone, such as lintels, 
pillars, projecting comers, carving, etc. All the classes were 
injured in these tests. The degree of heat reached in these 
experiments did not exceed 700° C, so it is safe to say that all 
thin edges of stone would suffer in a conflagration, possibly 
so much so as to need repairing. The tendency seemed to have 
been for the cubes to split off in shells around the point of great- 
est attack. This concentric peeling is seen in nature in the 
exfoliation of granite or other rocks in regions where there are 
decided changes in temperature, especially between the day and 
night. It has also been observed in buildings which were 



26 THE STATE GEOLOGIST. 

located in the burned districts of Paterson, Baltimore and San 
Francisco. 

At a temperature, then, which is probable in a fire, the finer- 
grained and more compact the stone and the simpler in mineral 
composition the better will it be able to resist the damaging 
effect of extreme heat. The sudden cooling by a stream of 
water will cause more injury than the slow cooling. Many of 
the samples assumed a brownish tinge upon being heated, due 
to a change of the iron present in the stone, from a ferrous to a 
ferric state. 

If the temperature does not exceed 550° C. all the building 
stones tested in this series will be little damaged, and they will 
resist injury in this order: limestone, sandstone, fine-grained 
crystallines, coarse-grained crystallines and clay rocks, the first 
being most resistant. If, however, the temperature be higher, all 
thin edges of stone work will suffer and the various stones tested 
in this set of experiments will resist in the following order, the 
first on the list offering the greatest resistance to injury; fine- 
grained compact sandstones, medium-grained dense sandstone, 
fine-textured granites, fine-grained gneisses, iinpure limestone, 
loose sandstone, coarse granite, coarse gneiss, clay rocks and 
pure limestone. 

Granites and Gneisses. — But two samples remained apparently 
unaffected after 550° C. slow-cooling test, those from Mont- 
ville and Waterloo (Plates III. and' VII.) The others suffered 
some, though very slight, injury. The cubes from Pompton 
Junction and Morristown show only a number of minute cracks 
on the polished surfaces, which do not seem to have weakened 
the stones. The small crack in the Dover sample (Plate V.) is 
in the coarser texture. All the other cubes tested at this temper- 
ature developed some small cracks. Those from German Val- 
ley, Montville, Mt. Arlington and Morristown were changed in 
color to a brown tinge, due, probably to a change in the con-- 
dition of the iron present in the stones. Usually, on fast cooling, 
a stone is more damaged than on slow cooling at the same tem- 
perature, but the two samples of gneiss from Cranberry Lake 
remained uninjured upon fast cooling, but were cracked some- 
what in the slow-cooling test. Upon fast cooling, at 550° C. all 



FIRE TESTS ON BUILDING STONES. 27 

the other cubes suffered some injury, though it was still slight ; 
the only severe case being the stone from Morristown, which 
had one bad crack extending around three sides of the cube. 

Upon slow cooling, at 850° C. we found that the damage was 
still worse, though in some cases yet comparatively slight. The 
sample of gneiss from Pompton Junction, which was the coars- 
est stone tested, was badly and irregularly cracked and lost some 
of its particles in the test (Plate IV). The Mt. Arlington and 
Waterloo samples developed a number of small cracks, and the 
latter looked' as if a blow would crumble it. The German Valley 
cube developed one open crack almost around the sample and the 
stone from Montville showed a number of small cracks. The 
cubes from Dover and Morristown were badly damaged, but in 
these cases the cracks were largely in the coarser seams. In the 
latter sample there was also a larger piece broken off one edge. 
Upon fast cooling at 850° C. we found that here, as in most cases 
in the 550° C. tests, the fast-cooled cubes were more injured than 
the slow-cooled ones, and all at this temperature in a fire, if 
cooled quickly by a stream of water would probably suffer great 
injury. The cube from Pompton Junction crumbled, those from 
German Valley and Montville were badly and irregularly cracked 
and lost some small spalls. Here, again, the cracks in those 
stones of varying textures seem to be more or less limited to the 
coarser seams. 

All the samples were injured by the action of the flame, though 
in varying degrees. The cube from Montville (Plate III.) was 
broken into two pieces; the Mt. Arlington sample was broken 
into a number of pieces (Plate VI.) and all the others, as can be 
seen by reference to the plates, lost pieces from the corners, and in 
all cases show some cracks, the Pompton Junction samples being 
badly cracked. Under the combined action of the flame and 
water, the Morristown sample lost a smaller piece from the at- 
tacked comer than in the flame test, but it was considerably 
more cracked. All the cubes suffered, both by losing pieces from 
the corners and by being cracked. The stones from German 
Valley, Dover, Mt. Arlington and Waterloo look as if a blow 
would easily crumble them. 



28 THE STATE GEOLOGIST. 

Judging* from these tests, most of these stones would stand a 
low heat quite well, especially if not cooled by a stream of water. 
At a higher heat, however, they would probably act badly, and 
if exposed in corners, on window sills and the like, they would 
suffer great injury. The finer-grained stones seem to stand up 
better than the coarser ones and in those stones in which there is 
a variation of texture the cracking seems to be greater and more 
severe, especially in the coarser seams. The cracking in the 
gneiss has a tendency to follow the banding, though this- is not 
a definite rule. A polished surface will show minute cracks, not 
noticeable on an unpolished face. 

Diabase, — Two samples of diabase were tested, a fine-grained 
variety from Plainfield and a medium-grained one from Lam- 
bertville; but we cannot compare these two, inasmuch as the 
Plainfield stone contains a number of calcite spherules, which 
very materially affected the behavior of the stone in the tests. 
It would be interesting to test a sample of this finer-grained stone 
containing no calcite. Then we could determine more definitely 
the factors controlling the refractoriness, for the composition, 
both mineralogical and chemical, would be practically the same 
and we would have only the difference in texture as a variable 
factor. 

In the 550° C. slow-cooling test the sample from Lambertville 
developed one slight crack around two sides. In the fast-cool- 
ing test, at this same temperature, the cracking was a trifle more 
marked, extending around three sides. The cube from Plain- 
field took on a brown tinge and developed several cracks. 

At 850° C. the Lambertville stone was little affected, showing 
only several very small cracks, but the cube from Plainfield was 
broken into numerous small pieces, due, probably, to the calcite 
giving off carbon dioxide in changing to CaO, and thus exerting 
a breaking pressure. In the rapidly cooled cube a similar re- 
sult was brought about, while the sample from Lambertville 
developed several cracks, one of which was opened and showed 
on three sides. 

Under the flame the Plainfield stone spalled somewhat on the 
exposed surfaces and developed one crack, while the Lambert- 
ville cube lost a one-inch piece from the corner and was slightly 



FIRE TESTS ON BUILDING STONES. 29 

cracked. Under the flame and water test the damage was, in 
bath cases, greater, larger pieces being broken from the corners 
and more cracks developed. 

Sandstones. — ^Among the sandstones there is much variation 
in the capacity of the different samples to resist the effect of ex- 
treme heat. Some seemed little affected, while others were badly 
injured. 

Some of the cubes, Pleasantdale ( Plate XVI ) , Avondale ( Plate 
XVII), North Arlington (Plate XVIII), and Closter (Plate 
XIX), remained uninjured on slow cooling, after having been 
heated to 550° C. On fast cooling the Pleasantdale and North 
Arlington samples developed slight cracks, while the cube from 
Closter still remained unaffected. A coarse variety of stone 
from Afvondale (Plate XVII), was uninjured by the sud- 
den cooling. The stones from Martinsville and North Arling- 
ton took on a brownish tinge because of the change in the condi- 
tion of the iron present. All the other samples showed some 
injury, though only slight, both on slow and sudden cooling, 
and in most all cases the cracks in the samples were parallel to 
the planes of lamination. 

In the 850° C. tests all of the stones were injured, though in 
varying degrees. The most pronounced cracks, in all cases, are 
along the bedding planes, though many of the stones also 
show transverse cracks. The samples from Stockton (Plate 
XIII) and Martinsville (Plate XV) were quite badly injured 
on slow cooling, and more so on fast cooling. Thfe cubes from 
Wilburtha (Plate XII), Avondale (Plate XVII) and 
Closter (Plate XIX) suffered much injury on rapid cooling. 
The sample from Pleasantdale (Plate XVI) came through the 
flame test with only slight cracks, and the Martinsville (Plate 
XV) and Closter (Plate XIX] cubes had but small pieces 
broken off from the comers. The others were much impaired. 

Under the action of the flame and water, the stone from 
Closter (Plate XIX) remained unchanged, but all the others 
had large pieces broken from the comers, and except those from 
Raven Rock (Plate XIV) and Martinsville (Plate XV), showed 
many cracks in addition. 



3Q THE STATE GEOLOGIST. 

. Limestones, — In both of the 550° C. tests all of the cubes re- 
mained apparently unchanged, except the sample from Phillips- 
burg, which developed several small cracks when cooled quickly. 

In the 850° C. series all the cubes were injured to a greater or 
le&s extent. The Franklin Furnace stone was badly injured, so 
much so as to make it worthless at this temperature (Plate XX). 
The cube from Phillipsburg developed some bad cracks, espec- 
ially along the veins of calcite, while the Newton sample stood 
the test fairly well. The Franklin Furnace stone was thor- 
oughly calcined on the outside, while the two other stones were 
little calcined, due to the impurity of the samples. 

In the flame tests all lost pieces from the attacked comer, be- 
sides showing several cracks in each case, the Newton cube 
suffering the greatest injury by being broken into several pieces. 
Under the action of the flame and water the injury was still 
greater, all of the samples being so broken as to render them 
useless. 

We see, then, that the limestones will stand up very well at 
550° C. ;: at 850° C. the coarser and more pure seem to have suf- 
fered the greater injury, and the sample ribbed with veins of cal- 
cite was injured more than the one with no such veins. All acted 
quite badly under the flame, and more so under the flame and 
water. 

Argillite. — This sample is an extremely fine-grained rock from 
Princeton, much like a shale, but which contains an abundance of 
calcareous material. 

Upon slow cooling, after having been heated to 550° C the 
cube was split along the bedding, besides showing other parallel 
cracks (Plate XXIII). Upon fast cooling some transverse 
cracks were developed, but most of the bad cracks extend par- 
allel to the lamination planes. 

The flame test developed one slight crack along the bed and 
around three sides, while the flame and water together broke a 
small piece off the upper edge, besides cracking the sample 
around three sides along the bed. 



Plates and Detailed Description of Tests. 



(30 



Plate I. 

Syenite, ]?rom Quarry o^ Lyman Kice, German Vali^ey, 

Morris County. 

This is a medium-grained greenish stone used for building 
purposes. It is made up largely of feldspar, with much green 
augite and some quartz. Under the microscope, the feldspar, 
which is very fresh, appears to be mostly microperthite and some 
plagioclase. The green augite and quartz make up the remain- 
der, with the exception of a few good crystals of zircon, some 
rounded apatites and a few magnetite grains. 

Fire Tests. ^ In all of the tests this sample suffered some in- 
jury, quite noticeable in the 850° C. tests, especially in the rapidly 
cooled tube, where the stone was very badly cracked. Under the 
action of the flame the injury was slight as compared to that of 
the flame and water test. In most cases the stone was discolored. 

No. 35. 550** slow-cooling test. No. 36. sso** fast-cooling test. 

No. 34. 850° slow-cooling test. No. ZJ- 850° fast-cooling test. 

No. 176. Flame test. No. 145. Flame and water test. 

' In all tests, the temperatures cited are Centigrade not Fahrenheit. 



(32) 



Geological Survey, igo6. 



Syenite. German Valley, Morris County. 



Plate II. 

Nos. 6y, 68, 177, 146. Gneiss from North Jersey Stone 
Company's Quarry, Cranberry Lake, Sussex County. 

This is a light-grey stone made up of light feldspar and 
quartz, with numerous small garnets scattered through the body. 
The quartz is less abundant than the feldspar, of which an acid 
plagioclase is the principal species, although orthoclase and 
some microcline microperthite are also present. The microscope 
also revealed the presence of some scales of biotite, which, in 
places had been bleached and in others had been altered to epidote. 
Some garnets and one zircon crystal were also noted in the 
section. 

Fire Tests. At 550° C. the stone acted well, the fast-cooled 
cube being apparently uninjured, while the slowly cooled sample 
showed but one small crack on one side. No samples were tested 
at 850° C. In the flame test the stone lost some small pieces and 
in the flame and water test it was damaged to a slightly greater 
extent. 

No. ^. 550'' slow-cooling test. No. 68. 550° fast-cooling test. 

No. 177. Flame test. No. 146. Flame and water test. 






Nos. 58, 59. Gneiss ^rom Panther Hill Granite Com- 
pany's Quarry, Cranberry Lake, Sussex County. 

The stone from this quarry, which, is used as a building stone, 
has a grey color and shows a good gneissic structure. Feldspar 
is more abundant than quartz, and the darker minerals evident in 
the hand specimen are hornblende and augite. The microscope 
showed the presence of much sphene. The green augite is more 

3 GEOL 



abundant than the green hornblende, to which it has altered in 
places. The quartz is less abundant than the feldspar, which 
is mostly an intergrowth of very acid plagioclase, some micro- 
cline and microcline microperthite. Rounded apatites are not 
rare and one scale of muscovite was noted in the section. 

Fire Tests. Only two tests were made on this stone, both at 
550^ C, in which the samples seem to have been little damaged. 
Upon slow cooling the cube showed one small crack at one 
corner, but not bad enough to seriously injure it. This stone, 
like many of the others, took on a brownish tinge. 

No. 58. 550° slow-cooling test. No. 59. 550'' fast-cooling test. 



(34) 



Geological Survey 1906. 



Gneisses. Cranberry Lake, Sussex County. 



PI.ATE III. 

Gneiss ]?rom the Jersey City Water Suppi^y Company's 

Quarry, Montvii^le, Morris County. 



The stone from this locality is very variable, both in texture 
and mineral composition. The coarser-grained kind is made 
up entirely of quartz and feldspar and some of the crystals are 
over one-half inch in size. The samples which were tested are 
medium grained and of a dark-grey color, composed of feldspar, 
quartz and some biotite. The stone was quarried only for use 
in the construction of the Boonton Dam. 

Fire Tests. Upon slow cooling at 550° C. the cube remained 
intact, and but a few small cracks were developed on rapid cool- 
ing. All these samples were changed in color to the brown, so 
characteristic of many of the stones. At 850° C. the samples were 
irregularly cracked, the fast-cooled cube slightly more so than 
the slowly cooled one. For the most part the cracks are par- 
allel to the gneissic banding. Under the flame the cube split 
into two large pieces, besides losing a small piece from the ex- 
posed comer, and while it did not break into two pieces under 
the action of the flame and water, it was considerably cracked 
and lost several small pieces. 



No. 84. 550'' slow-cooling test. 
No. 85. 550** fast-cooling test. 
No. 86. 850° sjow-cooling test. 



No. 87. 850° fast-cooling test. 

No. 178. Flame test. 

No. 147. Flame and water test. 



(3&) 



Geological Survey, igo6. 



Gneiss. Montville, Morris County, 



PI.ATE IV. 

Granite-Gneiss from Federai^ Hii.Iv Granite Company's 
Quarry^ Pompton Junction^ Passaic County. 



This is a pinkish stone which is used for general building pur- 
poses. It is very coarse-grained, some of the crystals having a 
size of over three-quarters of an inch; pink feldspar, smoky 
quartz and green hornblende are easily distinguished in the hand 
specimen. In some places the hornblende has weathered, thus 
giving a green stain to the stone. 

Fire Tests. This coarse-grained stone was little damaged in 
the 550^ C. tests. The slowly cooled cube developed some minute 
cracks on the polished face, more especially in the feldspars, 
which is due, probably, to the cleaveage. The fast-cooled sample 
shows several small, irregular cracks around the grains, not 
enough, however, to materially weaken the stone. In the 850° C. 
experiments the samples acted badly, the slowly cooled cube was 
considerably cracked and the fast-cooled one was so damaged as 
to cause the stone to crumble. This is probably due to the ex- 
treme coarseness of the grain. In the two flame tests the sam- 
ples lost small pieces from the exposed corners. 



No. 205. 550** slow-cooling test. 
No. 207. 850° slow-cooling test. 
No. 209. Flame test. 



No. 206. 550** fast-cooling test. 
No. 208 850** fast-cooling test. 
No. 210. Flame and water test. 



(3S) 



Geological Survey, igo6. 



itic Gneiss, Pompton Junction, Passaic County. 









• fe* 



PI.ATE V. 

Gneiss from Thomas Fanning^s Quarry, Dover, Morris 

County. 

This is a greenish stone used for structural work, of uneven, 
though prevailingly medium, texture and of irregular composi- 
tion. However, in the samples tested, quartz, feldspar and 
hornblende could be distinguished. 

Fire Tests. This stone assumed the brown tinge. In th€ 
tests at the lower temperature both of the cubes developed a 
small crack in the coarser seam, but these cracks are so slight 
that they would not probably affect the stability of the stone. 
In the higher temperature tests the cracking was so great as to 
injure the stones considerably, the cracks extending almost 
around the cubes. Here, too, the cracks seem to be confined to 
the coarser seams so frequent in the stone. The flame tests 
broke the pieces from the comers and developed some cracks, one 
very bad one in the cube which was subjected to the flame and 
water. 



No. 222. 550* slow-cooling test. 
No. 224. 850** slow-cooling test. 
No. 226. Flame test. 



No. 223. 550"* fast-cooling test. 
No. 225. 850° fast-cooling test. 
No. 227. Flame and water test 



(40) 



Geological Survey, 1906. 



Gneiss. Dover, Morris County. 



PlvATE VI. 

Gneiss from the North Jersey Stone Company's Quarry, 

Mt. Arungton, Morris County. 

This building stone has a gray color and is uneven in texture. 
The finer-grained parts seem to be made up of quartz, feldspar 
and black hornblende. The coarser seams give to the stone a de- 
cided gneissic structure. , 

Fire Tests. This is another- of the stones which took on a 
brownish tinge in the tests. The stones tested at 550° C. devel- 
oped some slight, but not serious, cracks. At 850° C. on slow 
cooling, several irregular cracks were caused, and on rapid 
cooling the stone was seriously cracked, but here, again, the 
cracks seem to be confined to the coarser seams. Under the 
flarne several pieces were broken from the corner and under the 
combined action of the flame and the water the cube was very 
materially injured. 



No. 228. 550° slow-cooling test. 
No. 230. 850° slow-cooling test. 
No. 232. Flame test. 



No. 229. 550° fast-cooling test. 
No. 231. 850° fast-cooling test. 
No. 233. Flame and water test. 



(42) 



Geological Survey, 1906. 



Gneiss. Mount Arlington, Morris County. 



PUiTt VII. 

Gneiss from North Jersey Stone Company's Quarry, Wat- 

ERI.OO, Morris County. 

The stone, which was tested, has a pinkish color, an uneven 
texture and a decided gtieissic structure. The minerals, which 
can be seen in the hand specimen, are pink feldspar, light quartz 
and green hornblende. 

Fire Tests. At 550° C. slow cooling this sample remained un- 
affected and on fast cooling developed but one small crack. The 
slowly cooled cube, at 850° C, has numerous small irregular 
cracks, and the fast-cooled one severial open cracks. The flame 
experiments greatly injured the cubes. Not only did they cause 
pieces to be broken from the exposed corners, but also caused 
some bad cracks in both samples. 



No. 234. 550° slow-cooling test. 
No. 236. 850° slow-cooling test. 
No. 238. Flame test. 



No. 235. 550° fast-cooling test. 
No. 237. 850° fast-cooling test. 
No. 239. Flame and water test. 



(44) 



Geological Survey. igo6. 



Gneiss, WateHoo, Sussex County. 



PI.ATE VIII. 

Gneiss f^rom Hibernia, Morris County. 

This is a gray gneiss of irregular texture, though prevailingly 
medium in grain, showing light feldspar, smoky quartz and a 
black hornblende or pyroxene. The quarry has not been worked 
for a considerable time. 

Fire Tests. The cube tested at 550° C. and cooled slowly re- 
mained unaffected. The sample heated to 850° C, and cooled 
rapidly, developed a brown tinge and was quite badly cracked. 
It looked as if a blow would easily crumble it. The cube, sub- 
jected to the flame and water test, was not only badly cracked but 
also lost several pieces from the comer. 

No. 240. 550** slow-cooling test. 
No. 241. 850° fast-cooling test. 
No. 242. Flame and water test. 



(46) 



Geological Survey, 1906. PLATE VIII. 



Hibernia, Morris County. 



» 

i 



Pirate IX. 

Gneiss ]?rom P. Lubey's Quarry, Morristown, Morris 

County. 

The stone from this locality is very variable, both in texture 
and composition. The cubes, which were tested, have a gneissic 
structure, a greenish color and are comparatively even in tex- 
ture. The entire mass has the appearance of a serpentinized rock. 

Fire Tests. The stone assumed a brownish tinge. Several 
small cracks developed on the polished surface after the cube had 
been heated to 550° C. and slowly cooled. The fast-cooled 
sample, at this same temperature, developed one bad crack around 
three sides. It is interesting to note that in this sample the cracks 
seem to have no definite relation to the direction of the gneissic 
banding, which is quite different from the usual relation. At 
850° C. both cubes were considerably damaged, so much so as to 
cause them to crumble. While the flame and water test did not 
disintegrate the cube so much as did the flame test, it developed 
considerably more cracks, so many as to cause the cube to 
crumble if struck a slight blow. 

No. 243. 550° slow-cooling test. No. 244. 550° fast-cooling test. 

No. 245. 850° slow-cooling test. No. 246. 850° fast-cooling test. 

No. 247. Flame test. No. 248. Flame and water test. 

Note the large crack in 246 and the corner of 247. 



(48) 



Geological Survey, 1906. 



Gneiss, Morristo\ 



4 GEOI. 



Plate X. 

Diabase from P. W. Wilson & Co/s Quarry, Plainfield, 

Somerset County. 

This is a very fine-grained rock of a greenish color, quj 
dense and hard, containing a number of spherules of calcite, soi 
of which are an eighth of an inch in diameter. 

Fire Tests. No cube was tested at 550° C. slow cooling, 
the fast-cooling experiment the stone assumed a brownish tii 
and showed one irregular crack around three sides, besides soj 
other smaller ones. In the 850° C. tests the samples were brol 
into a number of small pieces, due to pressure exerted by the 
caping carbon dioxide formed in the calcination of the calcj 
If the calcite were not present it is quite probable that the st( 
would have acted well. The flame caused some small craj 
and a number of spalls, while the flame and water broke a lal 
piece from the corner, a few spalls from the sides and develoj 
several small cracks. 

No. 200. 550° fast-cooling test. 
No. 201. 850** slow-cooling test. No. 202. 850° fast-cooling test. 

No. 203. Flame test. No. 204. Flame and water test. 



(50) 



Geological Survey, 1906. 



Diabase. Plainfield, Somerset County, 



Plate XI. 

Diabase, B. M. & J. S. Shanley's Quarry, Lambertvii.le, 

Hunterdon County. 

This stone has a greyish-black color and a medium texture. 
In the hand specimen much pyroxene and some feldspar can be 
recognized. 

Fire Tests. In the 550° C. tests the cubes were slightly cracked, 
the fast-cooled samples slightly more so than the slowly cooled 
one, but, in both cases, not enough materially to weaken the 
stone. At 850^ C. the cracking was more pronounced, but only in 
the rapidly cooled sample enough to damage it; here an open 
crack extends around three sides of the cube.* Small pieces were 
lost and several small cracks were developed in the flame tests. 



No. 255. 550** slow-cooling test. 
No. 257. 850° slow-cooling test. 
No. 259. Flame test. 



No. 256. 550° fast-cooling test. 
No. 258. 850** fast-cooling test. 
No. 260. Flame and water test. 



(52) 



Geological Survey, 1906. 



Diabase. Lambertville, Hunterdon County. 



PI.ATE XII. 

Sandstone, De Graves Bros. Quarry, Wilburtha, Mercer 

County. 

This stone is very variable, both in color and texture. The 
good stone is brown, fine-grained, quite compact and hard. 
Much of it is a poor grade, being soft and porous and of an un- 
even texture, even being coarse enough to be termed a conglom- 
erate in which quartz and weathered feldspar are easily dis- 
tinguishable. It is used for structural purposes. The stone, in 
the thin section, was seen to be composed of angular grains of 
quartz and much weathered feldspar, cemented rather loosely by 
limonite, thus leaving many pore spaces. Some plagioclase, 
biotite scales and ore grains, probably magnetite and pyrite, were 
also noted. The texture of the section examined is rather fine, 
the grains averaging one-fifteenth of a millimeter in diameter. 

Fire Tests. At 550° C. slow cooling the sample showed one 
crack around three sides, parallel to the bedding, and the rapidly 
cooled cube showed several, but not serious cracks. The tast- 
cooled cube, which was the only one tested at 850° C, was badly 
damaged. It split into two pieces along the bed, and one of these 
pieces in turn split into two across the bed. Besides this, sev- 
eral smaller cracks and some spalls were caused. In the flame 
tests both of the samples were broken in two along the bedding, 
and other smaller pieces were lost, the cube subjected to the 
flame and water being damaged to the greater extent. 

No. 64. 550° slow-cooling test. No. 65. 550° fast-cooling test. 

No. 66. 850** fast-cooling test. 
No. 172. Flame test. No. 140. Flame and water test. 



(54) 



Geological Survey, 1906. 



Sandstone. Wilburtha, Mercer County. 



'T*.. 



PI.ATE XIII. 

Sandstone, S. B. Twinning Co., Stockton, Hunterdon 

County. 

This is a hard compact stone of a light-gray to bluish color, 
used as a building stone. The blue variety is rather finer in tex- 
ture than the lighter stone, which is coarse enough in places to 
show quartz and weathered feldspar. The entire rock is spotted 
with limonite stains. The microscope showed angular grains of 
crushed quartz and weathered feldspar held together rather 
firmly by silica, some calcite and limonite. Among the feldspars 
microcline, plagioclase and microperthite were distinguishable. 
Patches of limonite were numerous. The grains vary somewhat 
in size, the. largest being over a millimeter in diameter and the 
• average about three-fifths of a millimeter. 

Fire Tests. Both of the cubes in the 550° C. tests showed but 
few slight cracks. But at 850° C. the samples were quite badly 
cracked. Here, as is different from the behavior in most sand- 
stones, the cracks are irregular. This is due to the coarseness 
of grain and the absence of distinct bedding planes. The samples 
assumed a slight brown tinge. The cube, which was subjected 
to the flame and water test, broke into a number of pieces. 

No. 47. 550** slow-cooling test. No. 49. 550** fast-cooling test. 

No. 46. 850® slow-cooling test. No. 48. 850** fast-cooling test. 

No. 141. Flame and water test. 



(56) 



Geological Survey, 1906. 



Sandstone. Stockton, Hunterdon County, 



.* 



PI.ATE XIV. 

Sandstone, Stockton Stone Co/s Quarry, Raven Rock, 

Hunterdon County. 

This sandstone, which is used for building purposes, is light 
gray in color, has an even texture of a fine grain and is quite 
compact. The microscope showed that the stone is composed of 
rather angular to rounded grains of quartz and weathered feld- 
spar cemented by limonite and calcite in a compact manner. 
Plagioclase, orthoclase, and microcline could be distinguished and 
a few grains, probably of magnetite and pyrite are scattered 
through the section. The grains average three-tenths of a milli- 
meter in diameter. 

Fire Tests. The rapidly cooled sample at 550° C. developed a 
few more cracks than the slowly cooled one, hut, in both cases 
the injury was slight. At 850° C, however, the cubes were badly 
injured. The slowly cooled stone showed up some irregular 
cracks, besides being broken into two. While the fast-cooled 
cube was not broken into two pieces it was considerably cracked. 
In both of the flame tests the exposed corners were broken. 

No. 50. 550° slow-cooling test. No. 51. 550° fast-cooling test. 

No. 52. 850° slow-cooling test. No. 53. 850° fast-cooling test. 

No. 173. Flame test. No. 142. Flame and water test. 



(58) 



Geological Survey, 1906. PLATE XIV. 



Sandstone. Raven Rock, Hunterdon County. 



PI.ATE XV. 

Sandstone, W. E. Barti^e's Quarry, Martinsvii<i.e, Somer- 
set County. 

* 

This stone, which is widely used for building purposes, is light 
gray in color, quite fine-grained and even in texture and fairly 
compact. The microscope showed that the grains are angular to 
rounded, average three-twentieths of a millimeter in size and are 
mostly quartz, though there is much weathered feldspar and some 
mica present. The cement is largely calcite, with some limonite. 
A few grains of mag^itite were noted in the section. 

Fire Tests. The rapidly cooled cube at 550° C. remained unin- 
jured, while the slowly cooled sample developed a small crack. 
This stone also took on a brownish tinge. At 850^ C, upon fast 
cooling, the stone showed one bad crack around three sides. 
Under the flame several small pieces were broken from the front 
edge, and under the flame and water test a much larger portion 
was lost. 

No. 'J2, 550° slow-cooling test. No. 73. 550** fast-cooling test. 

No. 74. 850** fast-cooling test. 
No. 175. Flame test. No. 144. Flame and water test. 



(60) 



Geological Survey, 1906, 



Sandstone, Martinsville, Somerset County. 



PI.ATE XVI. 

Sandstone^ F. W. Shrump's Quarry^, Pi,easantdai,k, Essex 

County. 

This building stone, brown in color, is quite variable. The 
good stone is fairly even grained and fine in texture, but it grades 
into a loose, coarse-grained stone, which, in places, splits very 
easily along the bed because of the presence of numerous scales 
of mica. Under the microscope the grains appeared to be sub- 
angular and are held together by a limonite cement. The stone 
is not very compact. The grains, which average one-tenth of a 
millimeter in diameter, are largely quartz and weathered feldspar, 
with some weathered mica scales and a few apatites. 

Fire Tests. Little damage was done in the 550° C. tests; the 
sample which was cooled slowly remaining unchanged and only 
one insignificant crack developing in the fast-cooled sample. At 
850° C. the cubes suflFered great injury; the slowly cooled stone 
split into two pieces and was otherwise badly cracked and the 
rapidly cooled sample was so injured as to make it worthless. 
Under the flame the stone resisted well, being cracked only 
slightly at the front edge, but under the combined action of the 
flame and water the sample was badly broken. 

No. yT. 550° slow-cooling test. No. 78. 550° fast-cooling test. 

No, 76. 850° slow-cooling test. No. 75. 850° fast-cooling test. 

No. 179. Flame test. No. 148. Flame and water test. 



(62) 



Geological Survey, igo6. 



Sandstone. Pleasantdale, Essex County. 



PI.ATE XVII. 

Sandstone, Bei.i.Evii,i,e Stone and Quarry Company, Avon- 

DAI.E, Essex County. 

The stone from this extensive quarry is a brown stone of a 
rather medium texture, firm and compact. The texture, as shown 
in the thin section, varies somewhat, the average size of the angu- 
lar and subangular grains being one-third of a millimeter, though 
there is much of a coarser and finer texture. Quartz and cloudy 
feldspar, with some plagioclase, make up most of the stone, 
though many colorless scales of mica are scattered through the 
mass. The cementing material is limonite and calcite in about 
equal proportions and the stone appears quite compact and firm. 

Fire Tests. The cube tested at 550° C. and cooled without the 
action of water remained unaffected. The' fast-cooled sample 
at 850° C. was split into two pieces along the bed and was also 
slightly darkened in color. The sample put through the flame 
split in two, showed several cracks and lost several pieces from 
the exposed edge. 

No. 108. 550° slow-cooling test. No. 180. Flame test. 

No. III. 850° fast-cooling test. 

Another sample, from the same .locality, is grayish brown in 
color and of a coarser and more uneven texture, the latter, as 
shown by the microscope, varying considerably. Some grains 
exceed a millimeter in size, while there is much that is finer. 
Quartz and feldspar with some microcline and microperthite are 
the sole constituents, with the exception of a few scales of color- 
less mica. The cementing material, as in the other sample from 
this locality, is limonite and calcite, though there is less of the 
latter in this stone than in .the brownstone. This sample is more 
compact than the brownstone. 

Fire Tests. The cube tested at the lower temperature remained 
uninjured, but assumed a brownish tinge. At 850° C. on slow 
cooling there were developed two slight cracks of marked irregu*- 
larity, differing in this respect from those in the finer-grained 
stone from this same locality. It would seem, then, that the 
coarseness of grain caused an irregularity in the cracking. The 
flame and water caused the cube to be so broken as to make it 
worthless. 

No. 109. 550** fast-cooling test. No. 149. Flame and water test. 

No. no. 850** slow-cooling test. 

(64) 



Geological Survey. 1906. PLATE XVII. 



Sandstone. Avondale, Essex County. 



5 GEOI. 



PI.ATE XVIII. 

Sandstone, Geo. Bayuss^ Quarry, North Arungton, Hud- 
son County. 

This stone, where fresh, is light gray in color, but, for the 
most part, it is stained with iron and copper compounds. Where 
fresh it is hard, compact and fine grained, but because of the 
amount of weathering it has undergone, it is rather loose and 
porous. It is locally used as a building stone. In thin section 
the texture was seen to vary somewhat. Most of the mass is fine 
grained, though some of the grains reach the size of a millimeter. 
The stone is made up of fairly rounded fragments of somewhat 
cracked quartz and cloudy feldspar, the latter mineral being the 
more abundant. As a whole the mass is loosely cemented by 
limonite, but in places there seemed also to be a cementing ma- 
terial made up of finely crystalline quartz and feldspar. 

Fire Tests. But three samples of this stone were tested. The 
550° C. slowly cooled cube remained uninjured, but assumed a 
slight brown tinge. The fast-cooled cube at this same tempera- 
ture developed one small crack across one corner. The sample 
after being subjected to the flame and water test went to pieces. 

No. 80. 550° slow-cooling test. No. 79. 550° fast-cooling test. 

No. 150. Flame and water test. 



(66) 



Geological Survey, 1906. PLATE XVIII. 



Sandstone, North Arlington, Hudson County. 



Plate XIX. 
Sandstone, J. GamblEE and Son, Closter, Bergen County. 

This stone is coarse grained and light gray, showing, in the 
hand specimen, weathered feldspar and quartz. It varies some- 
what in texture, yet is all quite coarse. The microscope showed 
that the mass is rather firmly cemented together and the grains 
are well interlocked. The cementing material is largely limonite, 
but the secondary enlargement of both the quartz and feldspar 
has made the stone firm and compact. The grains are irregular, 
angular and quite variable in size, the largest being over a milli- 
meter in diameter. Quartz, showing evidences of crushing, and 
feldspar make up the body of the stone in about equal proportions. 
The feldspar, which is somewhat weathered, is mainly an acid 
plagioclase and microline, with some microperthite and microcline 
microperthite. A few zircons and apatites were also noted in the 
section. 

Fire Tests. Both of the cubes tested at 550° C. remained unin- 
jured. The 850° C. slow-cooling test caused the stone to lose 
most of its durability, for it was split into a number of pieces by 
irregular cracks. In the flame test a small piece was broken from 
the exposed corner. Under the action of the flame and water the 
sample seems to have remained uninjured. 

No. 70. 550° slow-cooling test. No. 71. 550** fast-cooling test. 

No. 69. 850° fast-cooling test. 
No. 181. Flame test. No. 151. Flame and water test. 



(68) 



Geologica) Survey, 1906. 



Sandstone. Closter, Bergen County. 



5* GBOL 



PI.ATE XX. 

White Limestone^ B. Nicoi.1. & Co., Frankun Furnace^ 

Sussex County. 

This is an exceedingly coarse-grained, well-crystallized white 
limestone, some of the crystals of which are over two inches in 
size. The color is white to pale bluish. Scattered through the 
mass are scales of mica and graphite and other dark minerals. 
It is not used as a building stone. 

Fire Tests. A sample, after having been heated to 550° C. and 
cooled rapidly remained apparently uninjured. The 850^ C. tests 
badly damaged the cubes. Both were considerably cracked, cal- 
cined and -crumbled. Several cracks were caused and several 
small pieces were broken from the edge of the sample in the flame 
test and in the flame and water experiment large pieces were lost 
and small cracks developed. 

No. 211. 550** fast-cooling test. 
No. 212. 850** slow-cooling test. No. 213. 850° fast-cooling test. 

No. 214. Flame test. No. 215. Flame and water test. 



(70) 



Geological Survey, 1906. 



e (Marble). Franklin Furnace, Sussex County, 



PI.ATH XXL 

Limestone, O'Donnei. and McManiman's Quarry, Newton, 

Sussex County. 



This is a fine-grained, crystalline, blue and hard stone in which 
veins of white calcite locally occur. It is highly mag^esian. 

Fire Tests. Both cubes, in the 550° C. experiments remained 
unaffected. In the 850° C. tests the calcination was slight, because 
the stone is largely dolomitic. The slowly cooled sample shows 
several small and irregular cracks, the fast-cooled sample likewise 
shows several small cracks, and it flaked a little because of the 
calcination, but in both cases the injury is not great. In the 
flame tests the cubes were considerably affected, being broken 
into pieces on the exposed corners and edges. 



No. 216. 550** slow-cooling test. 
No. 218. 850** slow-cooling test. 
No. 22a Flame test. 



No. 217. 550° fast-cooling test. 
No. 219. 850** fast-cooling test. 
No. 221. Flame and water test. 



(72) 



Geological Survey, igo6. 



Limestone. "Newton, Sus 



V 



PI.ATE XXII. 

Limestone, Phii^upsburg, Warren County. 

This is a fine-grained, hard, crystalline dolomitic stone of a 
bluish color, in which are numerous, coarsely crystalline veins of 
calcite. 

Fire Tests. The 550° C. slowly cooled cube remained un- 
affected, but the rapidly cooled sample developed several small 
cracks. In both tests at 850° C. irregular cracks were caused 
along the calcite veins and there was some flaking due to the 
slight calcination. The flame test broke a small piece from the 
corner and caused several cracks. The combined action of the 
flame and water caused the sample to be broken into a number of 
pieces. 



No. 249. 550** slow-cooling test. 
No. 251. 850° slow-cooling test. 
No. 253. Flame test. 



Na 250. 550* fast-cooling test. 
No. 252. 850** fast-cooling test. 
No. 254. Flame and water test. 



(74) 



Geological Survey. 1906. PLATE XXII. 



Limestone. PhiUipsburg, Warren County, 



Pl^TE XXIII. 

* 

ARGII.UTE Rock, Margerum Bros., Princeton, Mercer 

County. 



The stone from this locality is an extremely fine-grained rock 
of a slate color. It looks much like a shale or a slate and splits 
readily along the bedding planes. It is used for structural work. 

The microscope reveals the presence of many cavities filled 
or partially filled with opal. Some little quartz grains are scat- 
tered through the mass, which seems to be an extremely fine- 
grained calcareous material, mixed with much clay. 

Fire Tests. Upon slow cooling, after being heated to 550° C, 
the cube was split along the bedding and showed other cracks. 
Upon cooling rapidly from the same temperature, some trans- 
verse cracks were developed, but the worse cracks were parallel 
to the bedding. The flame test developed one slight crack along 
the bed and around three sides, while the flame and water to- 
gether broke a small piece off the upper edge, besides cracking 
the sample around three sides along the bedding. 



No. 98. 550** slow-cooling test. 
No. 178. Flame test. 

Dec. 15, 1907. 



No. 99. 550° fast-cooling test. 
No. 143. Flame and water test. 



{76) 



Geological Survey, 1906. PLATE XXIII. 



Argillite. Princeton, Mercer County. 



PART n. 



The Glass-Sand Industry of New Jersey^ 



By HENRY B. KUMMEL and R. B. GAGE. 



6 GEOL (77) 



The Glass-Sand Industry of New Jersey* 



BY HENRY B. KUMMEL AND R. B. GAGE. 



Introduction, — This rqx)rt on the glass sands is part of a 
larger investigation of the sand deposits of the State, commenced 
nearly two years ago by the Geological Survey. Since numerous 
inquiries have been received for information regarding the glass 
sands in particular, the following paper has been prepared for 
publication at this time. 

Condition of the industry. — During the last ten or fifteen 
years the glass-sand industry of this State has witnessed a 
marked decline in the price received for sand, due to the intro- 
duction of labor-saving machinery and competition. There is 
also a tendency towards consolidation, which has resulted in the 
partial elimination of the small producer. This drop in price 
has stopped the mining of glass sand at some pits and caused the 
installation of modem plants to handle the sand on a larger scale 
at others. Those companies which have ceased to mine this 
grade of sand are mixing their glass sand with the top layers of 
the sandy loam and clay and selling the mixture for foundry 
purposes. This is particularly true when the glass sand is of an 
inferior grade, or else very small in amount compared to the 
foundry sand mined. 

Since there is practically little or no glass sand exported from 
the State, any cause that has a tendency to increase or decrease 
the prosperity of the glass industry of the State will naturally 
have a corresponding effect on the glass-sand industry. A rise 
in the price of the manufactured article, or decrease in the cost 
of producing the same, will encourage the manufacturer to en- 
large his output, which will increase the demand for sand. The 
•cost of labor being practically the same throughout the country, 

(79) 



8o THE STATE GEOLOGIST. 

the principal remaining factors that determine the prosperity of a 
glass industry in any particular locality are cost of fuel, sand and 
freight rates. 

The cost of fuel in the New Jersey field is high when com- 
pared to the cheap fuel available jn the natural gas fields of 
Indiana and Kansas, but experience has shown that the supply 
of natural gas is far from inexhaustible, and within recent years 
there have been many removals from the waning gas fields of 
Indiana to the new gas fields of Kansas. Even when compared 
with other fields using coal, the location of the New Jersey 
field is not particularly advantageous, although it is not greatly 
removed from the coal fields of Eastern Pennsylvania. It has, 
however, the tremendous advantage of close proximity to the 
markets of the large cities of the East. 

While the individual sand deposits of New Jersey are not . 
so large as those of the Middle West or Pennsylvania, they 
can be operated much cheaper and with a much smaller initial 
investment. The latter deposits are mostly sandstone, that 
must be blasted out and crushed before washing. Often these 
deposits are capped by shale or limestone of so great thickness 
as to compel mining by tunneling, instead of in an open pit. 
The New Jersey deposits are always capped by more or less 
sandy gravel, but this capping is not always a detriment in dig- 
ging, for it is sometimes profitably sold for foundry purposes. 
Again the New Jersey producer gets 90 ceiits per ton for his pro- 
duct, compared with 60 to 65 cents per ton in Illinois and Mis- 
souri.^ 

Area of the Held. — Throughout the -greater part of the south- 
ern half of the State, the surface gravel is underlaid by beds of 
sand. In some places these beds have been found to be 90 feet 
thick. Along the river banks they can be plainly seen where 
undercutting of the bluff has exposed them. These beds are 
often pure enough to be of value for glass, and are dug for this 
purpose. The principal localities in which they are being dug 
to-day are (i), along the Maurice River below Millville; (2), 
the region around Vineland, and ( 3 ) , that around Williamstown, 



*U. S. Geological Survey, Bulletin No. 285, p. 461. 



GLASS SAND INDUSTRY. 8i 

although twenty-five years ago glass sand was being mined as far 
east as Egg Harbor and west to Salem. The drop in the price of 
sand was probably the controlling factor that caused the con- 
traction in the area of the productive field. Since glass sand is 
widespread geographically, and the supply is always greatly in 
excess of the demand, only those pits which can be worked most 
cheaply have continued in operation. 

On account of the bulky nature of the sand, the cost of trans- 
portation is one of the leading items that determines the value of 
a pit, and consequently its life. This naturally confines the pro- 
ductive area of a glass-sand field to the vicinity of a railroad or 
navigable river. Practically every producing pit in southern 
New Jersey is less than one mile from a- railroad or is along a 
navigable stream, although there is no doubt but that good un- 
developed deposits of glass sand exist elsewhere in this region. 
Since cheap transportation is so vital a factor, there is small 
chance for the immediate development of the more distant areas. 
Even the territory that is within a mile of the railroads has not 
been thoroughly developed, or even tested. 

The prodiicing fields. — The present producing field is natur- 
ally divided into three districts, the Maurice River, the South 
Vineland and the Williamstown.^ 

The Maurice River district is just south of Millville, along the 
Maurice River, where the beds of sand can be seen for several 
miles along the river banks. The sand from this district is all 
shipped in barges, which fact naturally confines the pits to the 
banks of the river or a short distance inland. 

The West Jersey railroad traverses the South Vineland dis- 
trict, the village of South Vineland being about its center. All 
the pits are within J/2 to ^ of a mile of the railroad, and are 
scattered at irregular intervals for about 3 miles along it. 
This district would no doubt be much enlarged if the demand 
increased or the price rose sufficiently to justify operations at a 
greater distance from the railroad than at present. 

The Williamstown district covers a much larger area than 
either of the other two. The pits are scattered along the Wil- 

^Some glass sand is dug also at isolated points not included in these dis- 
tricts, as at Jamesburg, Middlesex county. 



82 THE STATE GEOLOGIST. 

liamstown and Delaware railroad from Downer nearly to Atco, 
a distance of lo miles. In most cases they are widely separ- 
ated, leaving plenty of undeveloped territory adjacent to the ' 
railroad. . Some new deposits have recently been discovered 
in this field, and are being developed. Judging from the size of 
the field, much good glass sand within this area is probably as yet 
undiscovered. If such is the case, this district alone could supply 
the demands of the glass industry for years to come. 

Description of the deposits, — ^All the glass-sand deposits of 
southern New Jersey are capped by layers of gravel, sand and 
loam, varying in thickness from i to 15 feet or more. Below 
Millville, along the Maurice River, the low hills are capped by 
gravel deposits, the thickness of this covering depending on the 
height of the hill, as little gravel is found in places below the top 
of the sand horizon proper, except as small pockets in the sand 
beds. These gravel deposits are, in many instances, of value for 
foundry purposes, road metal and other uses. The glass sands of 
this locality that are of commercial value all lie from 30 feet above 
sea level to a shallow depth below. The deposits are mostly on 
the west bank of the river, where the erosion of the river and its 
tributaries has exposed them. 

There is no doubt but that the sand beds extend an indefinite 
distance back from the river under the gravel capping, and at one 
point a small pit is now being worked about a mile back from 
the river. While there is no reason to suppose that the sand 
beds pinch out away from the river, nevertheless, the character 
of the sand may change from place to place so as to ruin it for 
glass purposes. The increased expense of opening up and work- 
ing a pit any distance from the river has discouraged operators 
from trying to discover new deposits in that direction. 

Several different grades of sand, sometimes as many as five, 
frequently occur in a single bank. These different layers vary- 
not alone in the iron and clay content, but also in the size and 
character of the sand grains. The various layers are frequently- 
separated by thin sheets of clay. Sometimes one grade changes 
abruptly into another, while elsewhere there may be a gradual 
transition from a fine to a coarse grain, or vice versa. Changes 
in the size of the grains are frequently accompanied by varia- 



GLASS SAND INDUSTRY. 83 

tions in the clay and iron content. Not uncommonly, the sand 
immediately below the gravel beds is fine grained, rich in clay 
and contains too much iron for glass use, but it is often mined 
and sold for foundry purposes. As the grains increase in size, 
the beds often become whiter with the lowering of the iron and 
clay content, until the best grade of glass sand is reached near 
the water level. Although the largest grains do not always 
occur at or below the water level, the beds of these grains are 
mostly lower in clay and other impurities than when composed of 
small grains. 

The topography of the South Vineland district is not so broken 
as that near Millville. The land is slightly rolling and mostly 
under cultivation. The overlying gravel, averaging only from 
3 to 5 feet, does not form- so thick a covering as in the Maurice 
River district. Immediately below the surface layer, the sand is 
sometimes finer grained than the glass-sand grade, but often dif- 
fers only in the amount of the clay and iron content. In the 
latter case, the sand gradually gets purer with depth until suit- 
able for glass. The ground waters apparently contain very little 
iron, as often the best grade of sand is found below the water 
level. Some of these pits have been worked over large areas, 
but seldom deeper than the water level. In mining, the stripping 
has been thrown on the mined ground, and no doubt has often 
covered first-class sand. From, the cursory examination made, 
it was impossible to tell whether the deposits pinched out at the 
edges or gradually became valueless for glass by becoming im- 
pregnated with iron. 

• Throughout the white sand there are frequently iron-stained 
streaks or seams, which are generally quite narrow and cause 
little or no trouble. Sometimes, however, they are 6 to 10 
inches thick, and then must be separated from the purer sand 
before washing. The sand above, between and below them may 
be first-class glass sand. 

Pockets of blue clay, sometimes of considerable size, occur not 
infrequently in the sand beds, but being sharply separated from 
them cause comparatively little trouble in mining. Sometimes 
layers of clay 2 to 3 feet thick are found just below the gravel 
covering resting on top of the glass-sand beds. 



84 THE STATE GEOLOGIST. 

The Williamstown district resembles the South Vineland dis- 
trict very much in topography, character and depth of the gravel 
covering. The fine, loamy foundry sand sometimes is wanting 
between the gravel layer and the white glass sand beneath. Often 
in different parts of the same bank, the foundry sand occurs at 
the level elsewhere occupied by the glass sand. In some of these 
pits, the best sand is found below the water level, while in other 
instances the percolating iron-bearing waters have ruined the de- 
posit below this point. In certain spots these chalybeate waters 
have coated the grains of the entire glass sand beds, rendering the 
deposit valueless at this point. Lenses of a clean, sharp small- 
pebbled gravel, which are of a different character than the gravel 
covering, are found in some of these sand beds. 

Mining methods, — ^There are two general methods of mining 
in use throughout the glass-sand field. By the older method, after 
stripping, the sand is shoveled into carts or cars and hauled to the 
washer. By the newer method, the sand, suspended in water, is 
pumped from the bottom of the pit and forced through a 4 to 
6-inch pipe to the washer. 

The former method has the advantage of producing a higher 
grade of sand than the latter method, where there is much varia- 
tion in the character of the beds, as the impure sand can be sepa- 
rated to a certain degree and discarded before washing, so that 
deposits can be mined by this method that would be worth- 
less if mined by the latter. The depth to which deposits can be 
dug by the old method is mostly determined by the height to which 
the ground water rises in the pit, as little sand is mined below the 
water level. In some pits this objection is of little importance,* 
as the sands are valueless below this point, while in other in- 
stances the best grade of glass sand is found below this level. 
The cost of handling sand by this method, however, is so much 
greater than by the pumping method that its advanta;ges are 
clearly outweighed by this one drawback, and therefore it is being 
rapidly replaced by the modern method at all pits where condi- 
tions are not absolutely prohibitory. 

A deposit to be mined by the pumping method must be. fairly 
uniform and free from iron-stained seams of any considerable 
thickness. One containing seams could not be mined at all by 



GLASS SAND INDUSTRY. 85 

this method, for washing- would not remove these iron-stained 
grains, and , they could not be removed otherwise, unless the 
seams are all found above the water level. In this case, they can 
be dug out separately before the sand falls into the water. The 
bottom of the deposit must also be a few feet below the level of 
the ground water, of which there must be a sufficient supply to 
keep the pit well filled in addition to furnishing what is needed 
for washing. In Plate XXIV this method of mining is fairly 
well shown. The white bank on the right is the glass sand, from 
which the overburden has been stripped off for a few yards back. 
' On the left is the waste pile of stripping which has been wheeled 
or carted across the bridge shown in the cut and dumped on the 
mined ground. Between these two banks a small, flat-bottomed 
boat, containing a suction pump and such other machinery as is 
necessary for pumping the sand and water, is seen in operation. 
The intake-pipe is kept a few feet under water and within a short 
distance of the sand bank. When this pipe is kept at the proper 
distance from the bank, the water pumped will contain from 20 to 
30 per cent, sand, the amount of sand carried and the size of the 
g-rains increasing with the velocity of the water. The mixture of 
sand and water is forced directly to the washer through the pipe 
seen leading off to the left. 

Any clay adhering to the sand grains is softened and de- 
tached from the grains during mining and washing, owing to the 
preliminary soaking to which it is subjected. With a medium- 
sized, well-equipped plant, 10 men can easily mine and wash 250 
tons of sand per day of 10 hours. 

The digging of glass sand requires quite an initial investment 
to open up a deposit and install a modern plant. Strong compe- 
tition between the different producers has lowered the price, so 
that, as already mentioned, at not a few pits which formerly pro- 
duced some glass sand, none is now mined. Those companies 
which do not adopt the newer methods will probably soon find it 
unprofitable to mine at the lower price, and must either install an 
up-to-date plant or else cease producing this grade of sand. 

Method of washing. — The method of washing glass sand in 
use throughout the New Jersey glass field is a comparatively 



86 THE STATE GEOLOGIST. 

simple process. The sand is washed into the upper end of an in- 
clined revolving cylindrical screen, about 4 feet long and 18 inches 
in diameter, and gradually works towards the lower end as the 
cylinder revolves. This screen allows all grains smaller than 
^/4oth of an inch (30 mesh) in diameter, to pass through into a 
trough below. Grains larger than this size pass out of the lower 
end of the cylinder and are rejected. The clay and loam, pass 
through the sieve together with the glass sand, so that this pre- 
liminary treatment eliminates only the material too coarse for the 
glass manufacturer. 

After passing through the screen, the sand is caried up a series 
of inclined flumes by endless chains and scrubbers (Plate XXV). 
As the sand passes slowly up these flumes the water runs back, 
carrying whatever clay and fine sand remains suspended in it. 
Impurities too heavy to remain suspended pass on with the sand, 
which is at last dumped in a pile outside the washer, where the 
excess of water is allowed to drain off before loading into cars. 
The scrubbers move so slowly up the nearly level flumes that only 
the fine clay and loam is removed. It is not uncommon to find 
in the washed sand ^ to i per cent, of the grains so fine that 
they will pass a 200-mesh sieve, and often 4 per cent, are finer 
than the 120-mesh sieve. If the scrubbers were made to travel 
faster or the flumes given a more inclined position, much more 
of this fine material would be removed, a result to be desired. 



PHYSICAL PROPERTIES. 

The physical character of a glass sand is of importance, al- 
though not so much so as the chemical composition. 

Shape, — It is the prevailing opinion throughout the glass-sand 
field that the sand grains should be sharp and angular, never 
rounded and smooth. This opinion does not" appear to be al- 
together well founded, as the ordinary grades of glass, as well 
as the fine flint wares, are being successfully made in the Missis- 
sippi Valley field from sands composed entirely of the latter type.^ 



*U. S. Geological Survey, Bulletin No. 285. 



GLASS SAND INDUSTRY. 87 

The New Jersey sands are prevailingly subangular. Most of 
the grains show irregular fracture surfaces, angles and edges, 
which in the case of those larger than ^/^^ of an inch (40-mesh) 
are more or less rounded, while of the grains smaller than ^/loo 
of an inch there are almost none which are not sharply angular. 
The grains of intermediate size are slightly worn, but not enough 
to change greatly their original shape. On the whole the sands 
would be classed as sharp and angular rather than round and 
smooth. The samples examined from the South Vineland district 
are somewhat more worn than those from the Williamstown. 

Plates XXVI and XXVII are photomicrographs of the sands, 
magnified 10:5 diameters, which show better than words their 
shape. 

Size, — ^The grains should not be too small or too large, and 
as uniform in size as possible. If the majority of the grains have 
a less diameter than 0.136 mm. (passing a sieve having 120 
meshes per linear inch), the sand is said to "bum out" in the 
batch and will not produce as much glass per unit as when 
composed of coarser grains. The fine grains also have a ten- 
dency to settle to the bottom of the batch, thus preventing the 
forming of a homogeneous mixture. When the grains are uni- 
formly larger than 0.64 mm. (30 mesh) in diameter, more time 
is required to fuse them than otherwise. This lowers the amount 
of sand each furnace can melt per day and increases the cost of 
the glass produced. 

The determination of the sizes of the grains can be best made 
by passing a known amount of sand through a series of sieves^ 
arranged in regular order, that with the coarsest mesh being at 
the top. A convenient quantity of the sand having been placed 
in the top sieve, the whole series, held firmly together is 
given a certain number of shakes, either by hand or in a machine, 
more rapid and satisfactory results being secured with a machine. 
After shaking, the amount found in the pan under the bottom 
sieve is weighed and the weight recorded. Then the amount 
found on the bottom sieve is added to that in the pan and the 

* A very convenient series of sieves reading from the bottom up according 
to mesh are 200, 140, 120, 100, 80, 60, 40, 30, 24, 18, 10, J4» Vi« and 1/2. 



88 



THE STATE GEOLOGIST. 



whole weighed and recorded. This is continued until that found 
on all the sieves has been weighed, and the amount that has 
passed each sieve determined. If a weight of loo grams were 
originally taken, the percentage which has passed each sieve can 
be read directly from these weights without further calculation. 
Samples of washed glass sand from many of the deposits in 
the State have been examined by the above method, with the 
results shown in the following table: 

Table showing the per cent, of grains passing the different sieves. 



MESH OP 
SIEVE. 


661B 


664A 665C 


666A 


669A 


670B 


671A 


672A 


663 


10 


99.8 
99.7 
99.4 
98.3 
93.7 
53.1 
26.S 

5.2 
2.3 
0.7 






99.7 
99.5 
98.4 

93.7 
73-6 
22.2 
II. I 

2.5 
1.4 
0.4 








99.8 
99.2 

98.5 
95.8 

85.4 

25.4 

11.5 

1.4 

0.5 

0.0 


99.8 
99.7 

00.'? 


l8, 












24, 


* '99.8' 
97.8 
18.8 
6.2 

17 

I.I 

0.5 


99.5 

9a6 

81.9 

1 1.4 

37 

0.5 
0.2 

0.1 






99.8 

99.1 

96.3 

40.4 
22.6 

4.4 
2.2 

0.8 


30, 

40, 

6o, 

8o 

120, 

140, 

200, 


99.7 
98.8 

19.5 

7-7 
1.6 

I.I 
0.5 


99.8 
99.2 
47.8 
16.2 
2.6 

1.5 
07 


96.4 

61.4 

7.4 

1.8 
0.2 
0.0 
0.0 



From the above table it is apparent that in none of the samples 
is there much material which will pass a 120-mesh sieve (open- 
ings ^/i87 inch) and very little (except in No. 666A and 663) 
which is coarser than a 40-mesh sieve (openings ^/^g inch). In 
many of the samples about 60 per cent, of the grains are between 
V55 and V90 inches in diameter (40 and 60-mesh). Sample 663 
of the table is a Pennsylvania sand cleaned by an air-blast process 
rather than by washing. It has 35 per cent, of the grains between 
V40 and ^/gg inches in diameter and 54 per cent, between 
^/gg and V90 inches, with an entire absence of grains smaller than 
^Aio inches (140 mesh) and practically none as small as ^/isi 
inches (120 mesh). These statements and the above table indi- 
cate the comparative uniformity in the size of grain of a good 
glass sand. 

Examination of a number of unwashed sands disclosed a 
slightly larger percentage, as compared to the washed sands, of 



Geological Survey, igo6. PLATE XXVI. 



Pig- I- 

Well-rounded sand grains from an Ordovician Dolomite, Cushman, Ark. 

(van Ingen) — magnified 15 diam. 



Fig. z. 

Sand grains retained on a 40-mesh sieve, x loj^ diam. Reading Sand 

Company, Penbryn. 



Geological Survey, 1906. PLATE XXVII. 



Fig. I. 

Sand from WeJrick and Fields. Radix, x loH diam. Note a f«w 

rounded grains. 



fii. I. 

Sand from Crystal Sand Company, South Vineland, x io% diam. 



GLASS SAND INDUSTRY. 89 

the sizes rejected in the process of washing already described, 
but these differences are not striking. 

Impurities. — ^Under the microscope the quartz grains appear 
as clear, transparent crystals. Grains of milky or colored quartz 
are very rare, and there is little evidence of any impurities such 
as clay or iron oxide attached to the grains of either the washed 
or unwashed sands. Small grains of other minerals than quartz 
are quite numerous in the Williamstown deposits, but much less 
so in the samples from the other two fields. These foreign grains 
are fairly uniform in size, well-rounded and mostly less than 0.21 
mm. (^/i2i inch) in diameter, and will pass an 80-mesh sieve. 
They were found to be chiefly leucoxene, rutile, ilmenite and 
sphene.^ Since the quartz grains are almost chemically pure 
themselves and have practically no impurities attached to them, 
these minerals must contain the greater part of the iron, titanium, 
etc., which chemical analysis shows are present in the sands. It 
follows that if they can be eliminated the quality of the sand will 
be much improved. 

Chemical composition. — ^An absolutely pure quartz sand would 
be 100 per cent, silica (Si02), but an accurate chemical analysis 
of even the best glass sands always shows small amounts of the 
following substances : iron, alumina, titanium oxide, lime, mag- 
nesia and organic matter. These are due to other mineral grains 
than quartz usually present in the sand, such as mica, magnetite, 
feldspar more or less altered to kaolin, ilmenite, sphene, rutile, 
etc., or to films of iron oxide or clay coating the quartz grains. 
Some of these cause little or no trouble in a glass sand when pres- 
ent in small amounts, while others are very injurious when pres- 
ent even in amounts not to exceed ^/loo o^ ^ P^ ^^^^' Chief 
among these detrimental substances are the oxides of iron which, 
if not already in the ferrous state, are reduced to it in the furnace, 
and give the glass a green color. Such substances, as the car- 
bonate of lime which may occur as bits of shell or ground-up 
limestone can hardly be classed as impurities, since they are added 
to the sand in the manufacture of glass, altjiough when present 
in the sand they lower the percentage of silica, as shown by the 



* Examined and identified by Prof. J. Volney Lewis, of Rutgers College. 



90 



THE STATE GEOLOGIST. 



analysis. The oxides of sodium and potassium which are shown 
in small amounts in some analyses of glass sands are not to be 
regarded as impurities, as they also are added in making up the 
glass batch. A small percentage of clay causes little trouble pro- 
viding the clay contains no iron and very little magnesia, but this 
is very seldom the case. The water coming from the scrubbers 
is almost always a dirty yellow color which indicates the presence 
of clay containing considerable iron, some or all of which is in the 
ferric state. The following chemical analyses of New Jersey 
washed glass sands and of one Pennsylvania sand (663) have 
been made especially for this report by the junior author: 



Sample No. 





Iron 




Titanium 






Silica 


Oxide 


Alumina 


Dioxide 


I«ime 


Mafniesia 


SiO,. 


Fe.O,. 


Al.G,. 


Tic.. 


CaO. 


MgO. 



Organic 

Matter 

and 

Moisture. 



661 B, 

662A, 

663, 

664B, 

665C, 

666A, 

667A, 

668A, 

669A, 

669B, 

670A, 

671A, 

672A, 

673A, 



98.93 % 

99.59 

99.72 

99.40 

99.62 

9954 
99.35 
99.52 
99.42 
99.48 
99-39 
99.11 
99.176 

99-55 



0.0222% 
0.0071 " 
0.0017 " 
0.0058 " 
0.0047 " 
0.0039 " 
0.0086" 
0.0096" 
0.0068" 
0.0075 " 
0.0086" 
0.0108 " 
0.0114" 
0.0049 " 



0.4686% 

0.1447 " 
0.1203 " 

0.2752 " 
0.142 " 
0.2245 " 
0.3392 " 
0.1856" 
0.276 
0.204 

0.2345 " 

0.355 
0.366 

0.1443 " 



tt 



tt 



ft 



tt 



0.269 % 
0.0728 
0.0147 
0.0737 

0.0543 
0.0476 

0.1302 

0.0868 

0.1 17 

0.1215 

0.1475 
0.2213 

0.2344 
0.0608 



0.010% 

O.OIO " 

0.007 " 
0.008" 

0.01 " 

0.007 " 
0.017 " 
0.006" 

0.01 " 

0.006" 

0.005 " 
0.009" 

O.OII " 

0.008" 



0.008% 
0.007" 

0.008" 

0.012 " 
0.005 " 
0.009" 
0.005 " 
0.007" 

0.018 " 

0.009 
0.007 
0.023 
0.019 

O.OII 



(( 



(( 



(( 



(( 



(( 



0.29 % 
0.172 

0.134 
0.231 

0:162 

0.166 

0.156 

0.19 

0.156 

0.17 

0.21 

0.19 

0.182 

0.22 



Samples Nos. 664B, 665 C, 666A and 673 A are fairly good 
sands for all ordinary kinds of glass, and are often used for flint 
glass, but have to be corrected when thus used. Their chief use, 
however, is for window, green and amber glass. Sands like 671A 
and 672A are used only for the cheaper grades of glass where 
the color makes little difference, as in beer bottles. Sample No. 
663 is a Pennsylvania sand which is used extensively by the New 
Jersey glass manufacturers for the best grades of flint glass. 

In regard to these analysis, it is hardly necessary to point out 
that they show the composition of the sample analyzed, not neces- 
sarily the true average chemical composition of the whole de- 
posit. While care was taken to select a fair sample, yet the 



GLASS SAND INDUSTRY. 91 

amount of sand exposed at any one time during the life of a pit 
is a^ very small proportion of the total, and there is no reason for 
believing that the sand may not vary slightly in chemical com- 
position from place to place. 

The whiteness of these sands, often relied upon as a test of 
their purity, is a very poor indication of the iron content. Sample 
No. 672A is equally as white in appearance as sample 666A, but 
the analysis given above shows the former contains more than 
three times as much iron as the latter. If the iron were present 
as ferric oxide coating the quartz grains, or as one of the bases 
in a clay which was attached to the grains, the color might be a 
guide to the iron content, but this is not the case. Under the 
microscope the quartz grains are seen to be clear and colorless, 
and are not stained by iron oxide. We have pointed out that 
the sand contains numerous dark-colored minerals, which were 
identified under the microscope as leucoxene (probably), rutile, 
ilemenite and sphene, their relative abundance being indicated by 
the above order. These are heavier than the quartz, and with 
slight shaking readily settle to the bottom of a sample. They are 
also of a somewhat uniform size and will pass an 80-mesh sieve. 
The amount of iron and titanium foimd by analysis is readily 
explained by the presence of these minerals in the sands, and one 
cannot question the conclusion that the iron content which is 
especially detrimental, is due solely to these minerals, particularly 
to the ilmenite. If, therefore, some method can be devised 
whereby they can be eliminated without too great expense and 
the loss of too large a proportion of the quartz sand, the value 
of the remainder will be greatly enhanced. By the present method 
of washing in use throughout the glass-sand field, no effort what- 
ever is made to remove them. They have apparently been over- 
looked, or else little importance has been attached to them. 

The presence of these heavier minerals in the sand makes it 
difficult to obtain a sample which is a fair average of the whole 
bank. There was more or less concentration of them during the 
deposition of the beds, so that the composition of the sand varies 
•from place to place. During transportation, the jarring of a 
loaded car, particularly if the sand be dry, is sufficient to cause 
considerable concentration of the heavier minerals toward the 



92 THE STATE GEOLOGIST. 

bottom. Under these circumstances a sample taken from the 
top of a load may fail to represent the correct composition of the 
sand. If the sand is wet, this concentration during transportation 
does not occur, at least to so great an extent. 

The iron imparts a green color to the glass, an effect which the 
manufacturer sometimes attempts to neutralize by the addition of 
manganese dioxide. Since, however, an excess of manganese 
gives a pink color, the importance of an accurate determination 
of the iron content is manifest. When the iron content of the 
sand is fairly uniform, this is comparatively easy, but when this 
is not the case the iron value of the sand must be constantly 
checked by chemical analysis. We have been informed by one of 
the glass manufacturers that this variation of the iron content 
was one of the greatest objections to New Jersey sands for flint 
glass. No two carloads were apparently the same, and some- 
times the sand in different parts of the same car varied con- 
siderably. These facts may be due in part to the concentration of 
these heavy minerals in certain parts of the bank during deposi- 
tion and in part to the concentration of these minerals in the 
bottom of the car during transportation. 

Bliniination of the iron, — The fact that the minerals containing 
the iron will nearly all pass an So-mesh sieve, at once suggests 
the possibility of cleansing the sands by sieving. This was done 
in the laboratory with two dry samples, numbers 669A and 
672A. Convenient quantities of these two sands were thoroughly 
shaken in an 80-mesh sieve, and then the iron, titanium and 
alumina in the part remaining on the sieve were determined and 
the results compared with the previous analysis, as shown below : 

Sample No. 66gA. Sample No. 672 A, 

Before After Before After 

Constituents. Sieving. Sieving. Sieving. Sieving. 

FcaO* 0.0068 0.0022 0.0114 0.0029 

TiOa 0.117 0.024 0.234 0.0434 

AUOa 0.276 0.085 0.366 0.106 

By this sieving process the amount of iron in the sample was 
reduced to one-third or less, of titanium to one-fifth, and of 
alumina to one-third or less. The lime and magnesia being so 



GLASS SAND INDUSTRY. 93 

low in the original samples, were not determined in the sieved 
portions. These sands, which previous to sieving were only 
second-grade sands on account of their iron, were by this means 
rendered suitable for the manufacture of the best grades of flint 
and plate glass, the iron content being as low as in sample No. 
663 which is used for this purpose. The samples thus treated 
compare very favorably with the sands used by the Pittsburg 
Plate Glass and the American Window Glass Companies, as 
shown by the following analysis : 

Analysis of sand used by the Pittsburg Plate Glass Co} 

Constituents. No. i. No. 2, No. 3. No. 4. 

Silica (SiCX), 99.21 98.90 98.95 98.94 

Alumina ( AUOs) , 30 .20 .50 .30 

Volatile matter, 21 .25 .24 .23 

Iron oxide (FeaOs) , 003 .002 .0024 .0036 

Lime (CaO), 20 .54 .30 .40 

Magnesia (MgO), trace .20 .10 trace 

99.923 100.092 100.0924 99.8736 

When sands of the above composition are used no correction 
for color is attempted in manufacturing plate glass. 



Analysis of sand used by American Window Ghass Co 



2 



Constituents. No. i. No. 2. No. 3. No. 4. 

Silica (Si02) , 99-99 99714 99-659 99-579 

Alumina (AUOa), 008 .280 .310 .350 

slight 

Iron oxide (FeaOa), trace .006 .011 .021 

Lime & magnesia (CaO & MgO), 002 .020 .020 .050 



100.00 100.00 100.00 100.00 



It is to be noted further that our sieving removed not only a 
large percentage of the objectionable minerals, but it also re- 



*U. S. Geological Survey, Bulletin No. 285. 

* It is to be noted that no water determination appears in these analyses, 
and the silica is taken by difference. Consequently, the silica is just as much 
too high as the amount of water carried by the sand. Taken from U. S. 
Geological Survey, Bulletin No. 285. 

7 GKOI. 



94 THE STATE GEOLOGIST. 

moved all the fine grains under Somesh size. Reference to the 
tables of physical tests on p. 88 shows that in five of the eight 
samples the part passing this sieve is ii per cent, or less 
of the whole; in three cases it is considerably more. The 
elimination of these finer grains would make the sand more de- 
sirable from a physical standpoint, and probably add something 
to its value. The Pennsylvania sand, No. 633, contains less 
than 2 per cent of grains finer than an 80-mesh, and it is also 
low in iron. Large amounts of it are imported by New Jersey 
glass manufacturers annually at a cost of about $3.00 per ton. 
If by sieving, the New Jersey sands can be raised, both chem- 
ically and physically, to the grade of this Pennsylvania sand, 
and enhanced in value from 90 cents to $3.00 per ton thereby, 
the problem is worth careful consideration by glass producers. 

We have indicated that on the average from 10 to 15 per cent, 
of sand grains, practically all including the iron-bearing minerals, 
passed the 80-mesh sieve. This fine-grained sand would there- 
fore be valueless for glass purposes, but it might not all be a loss, 
since sand grains of this size are always sharp and angular and 
so will cut much faster than rounded grains. There might be, 
therefore, a market for it as grinding material. But even if 
there were not, the New Jersey sand producer could well afford 
to sacrifice 20^per cent, of his product if the remaining 80 per 
cent, could be cheaply raised to the grade of the high-priced sand 
imported from Pennsylvania. 

We are aware that it is one thing to sieve thoroughly a small 
quantity of dry sand in a laboratory and eliminate the finest 
grains and the iron minerals, and quite another thing to treat 
wet sand effectively and cheaply on a commercial scale and in 
large amounts. We have hopes, however, that the inventive 
genius of the sand producers may make some use of this sugges- 
tion. We do not need to emphasize the importance to the indus- 
try of improving the grade of sand if it can be done cheaply. 

It is not claimed that the size of the screen used in these ex- 
periments is the one that would always give the most satis- 
factory results in actual practice. These impurities vary in size 
in different deposits, so that a screen of another mesh might be 
needed in some localities to get the best results. 



GLASS SAND INDUSTRY. 95 

« 

If it be found impossible in practice to remove these grains by 
washing or sieving, there remains the question of magnetic 
separation, which has worked so successfully in late years with 
various kinds of ore. 

Ilmenite and magnetite are both magnetic, as are many other 
iron-bearing minerals, and in a dry sand can very probably be 
concentrated by the magnet. Whether the process would be suc- 
cessful with the wet sand as it comes from the pits and washeries, 
and whether it could be economically carried out, are questions 
which we cannot enter upon here. 

Production. — ^As a producer, New Jersey is surpassed by 
five States in the amount of glass sand produced, and by only 
four States in value of the product. While the West Virginia and 
Pennsylvania producers get on the average $1.50 and $1.31 at the 
mines, respectively, per ton for their product compared with 80 to 
90 cents in New Jersey, the former deposits are much more expen- 
sive to operate than the latter. The Illinois and Missouri pro- 
ducers, however, get only about 60 cents per ton. 

During the summer &i 1906, the following firms were digging 
glass sands : 

Pit 

No. Owner. Location of Pit. 

661 Crystal Sand Co., Maurice Riv^r below Millville. 

662 Crystal Sand Co., Cedarville. 

664 R. O. Bidwell, South Vineland. 

665 John Burns, South Vineland. 

666 Crystal Sand Co., North Pit, South Vineland. 

667 Crystal Sand Co., South Pit, 'South Vineland. 

668 S. W. Downer, Downer. 

669 Weirick & Fields, Radix. 

670 Reakirt Glass Sand Mining Co., Sicklerville. 

671 A. L. Thomas, Tansborough. 

672" Reading Sand Co., Penbryn. 

673 Wm. Ranagan, South Vineland. 

McCoys, - South Vineland. 

Appleby Sand & Clay Co., Old Bridge. • ' 

Henry Wagner, 

Asa Redrew, 

A table showing the amount of glass sand mined in 1905 in 
the different States and value of the same is given below, based 
on statistics published by the United States Geological Survey. 



96 THE STATE GEOLOGIST. 

Short tons. Value. 

Pennsylvania, 361,829 $482,937 

Illinois, 234,391 146,605 

West Virginia, 155,052 225,734 

Missouri, 123467 66,401 

Ohio, 74,460 79,999 

New Jersey,^ 35,673 30,005 

Maryland, 17,899 20,108 

California, 9,257 8,112 

Massachusetts, 4,600 12,000 

Georgia, 4,500 4,050 

New York, 3,165 3,115 

Summarizing the principle facts regarding the glass-sand de- 
posits of New Jersey, which have been discussed more or less in 
detail above, they may be said to be chiefly these : 

ist. The supply of glass sand is sufficient to meet the demands 
of the glass industry for an indefinite period. 

2d. There are apparently numerous undeveloped deposits ad- 
jacent the present railroad lines. 

3d. The chances of finding good deposits in localities remote 
from the present railroads are equally as good as in localities ad- 
jacent thereto, but without cheap transportation they cannot be 
utilized at present prices. 

4th. The deposits are of fairly good size and can be developed 
at a low initial cost compared with the deposits of Pennsylvania 
and the Middle West. 

5th. The physical character of the sand equals, if it does not 
exceed, that of the western fields. 

6th. The sand as mined to-day is well suited for the manufac- 
ture of green, amber and window glass. 

7th. By the elimination of the iron-bearing minerals, either by 
sieving, improved methods of washing or perhaps by magnetic 
separation, the New Jersey product can probably be made suitable 
for the manufacture of flint and plate glass. 

8th. They are well located regarding shipping facilities and 
the markets of the large cities of the East. 

April 2, 1907. 

^ Figures obtained by the State Survey indicate that the above production 
for New Jersey is far below the actual product. Twenty glass manufacturers 
within the State report using 50,692 tons of New Jersey glass sand for year 
ending June 30, 1906. The total actual production in 1906 was probably over 
100,000 tons. 



. 



PART m. 



The Origin and Relations of the Newark 

Rocks* 



The Newark (Triassic) G^pper Ores of 

New Jersey, 



Properties of Trap Rocks for Road 

Construction, 



By J. VOLNEY LEWIS. 



(97) 



The Origin and Relations of the Newark Rocks* 



BY J. VOI.NEY I.EWIS. 



CONTENTS. 

Introduction. , 

Extent of the Newark System. 
Characters of the Sedimentary Rocks. 
Sources of the Sediments. 
Origin of the Sediments. 

The Tidal Estuary hypothesis. 
The Lake Basin hypothesis. 
Objections to the foregoing hypotheses. 
Hypothesis of Orographic Valleys. 
Objections to the Orographic Valley hypothesis. 
A Piedmont Plain hypothesis. 
Geologic Relations of the Trap Rocks. 
Relations of the Extrusives. 

The Watchung flows. 

The double crest of Second Mountain. 

Sand Brook and New Germantown extrusives. 
Relations of the Intrusives. 

The Palisades, Rocky Hill, Sourland Mountain, Byram. 

Offshoots of the Palisades sill. 

Cushetunk and Round mountains. 
Origin of the Trap Rocks. 

Origin of the First Mountain extrusive. 
Origin of the double flow of Second Mountain. 
Origin of the Long Hill extrusive. 
Origin of the Intrusive Trap masses. 
Deformation and Erosion. 

The supposed fault along the Hudson River. 
Age of the faults. 

INTRODUCTION. 

Extent of the Newark System, 

The Newark (or Triassic) system, of New Jersey (PL 
XXVIII) is part of a long, narrow belt extending from southern 

(99) . . , .] 



lOO 



THE STATE GEOLOGIST. 



New York southwestward across New Jersey, Pennsylvania, 
Maryland, and northern Virginia, as shown on the outline map, 
Pig. I, and this is but one of several similar disconnected areas 
in the Atlantic coastal region from Nova Scotia to Sbuth Caro- 
lina. The belt across New Jersey occupies about one-sixth of the 
total area of the State, extending from the Hudson River and 
the New York State boundary to the Delaware River. It com- 
prises the Piedmont region, which is intermediate in elevation 



■• 







AREAS 
OCCUPIED BY THE 

NEWARK SYSTEM 






0:S,0BOUM»CAC SCRVEV' 



j^mtui. 



Fig. J. 

and surface features between the low, smooth Coastal Plain to the 
southeast and the higher and more mountainous Highlands to 
the northwest. Its undulating surface is interrupted by several 
conspicuous ridges, notably the Watchung Mountains and the 
Palisades in the northeast and Cushetunk, Round and Sourland 
mountains and Rocky Hill in the southwest. 

The rocks of this system have been fully described in the pre- 
vious reports of this Survey, particularly by Kiimmel^ about a 



^:APtnu9j[ Reports of the State Geologist for 1896, pp. 25-88; 1897, pp. 23-159. 



ORIGIN NEWARK ROCKS. ' loi 

decade ago. In connection with recent studies of the petro- 
graphy of the trap rocks and the occurrence and origin of the 
copper ores, however, some conclusions have been reached which 
are at variance with views heretofore published, and these are 
set forth in the following pages. 



Characters of the Sedimentary Rocks. 

The sedimentary rocks of the Newark system, as is generally 
known, are chiefly fine-grained red shales, with some sandstones 
and conglomorates (Brunswick), and, at some horizons, thick 
black argillites which do not readily split into thin layers 
(lyockatong). Coarse conglomerates occur not only nesir the 
base of the series, but also near the top and at various intermedi- 
ate horizons. Heavy-bedded- sandstone also occurs at various 
levels, chiefly, but not exculsively, in the lower part (Stockton). 
Associated with the black argillites are gray and green flagstones, 
and occasionally thin layers of very calcareous shale; but the 
great mass of the formation in its most characteristic phase is a 
soft red shale, in which occasional layers of purple, green, yellow 
and black shales occur. 

"Ripple-marks, mud-cracks and raindrop impressions occur at 
many horizons. In some quarries impressions of leaves and 
stems of trees, or the stems themselves, are not infrequently 
found. Occasionally slabs are found bearing the foot-prints of 
reptiles and other vertebrates which wandered over the soft mud- 
flats while these beds were in process of accumulation.'' ^ Cross- 
bedding, or plunge-and-flow structure, and rapid variations of 
texture in the individual beds are also common characteristics of 
the coarser sediments. 



Sources of the Sediments. 

Many of the sandstones, particularly the coarser ones, are 
feldspathic and have numerous flakes of mica, all of which are 



^Kiimmel, Ann. Rep. of State Geologist, 1897, p. 42. 



102 . THE STATE GEOLOGIST. 

products of the disintegration of granites and gneisses, with little 
decomposition. The conglomerates sometimes contain gneissic 
pebbles, but most of them are composed of fragments broken from 
Paleozoic quartzites and limestones. The purer sands are doubt- 
less residual grains from decomposing granites and gneisses and 
from crumbling quartzites. The shales are consolidated mud- 
beds, derived from residual soil of limestones and from the de- 
composing feldspars of granites and gneisses. All of these ma- 
terials were washed down from the adjacent Highlands, the dis- 
integration and decay of the underlying rocks renewing the soil 
as it was gradually removed by erosion and carried away by the 
streams. 

It is not necessary to suppose that the lands were covered with 
an unusual thickness of such materials, for the period of dego- 
sition was of vast duration. We need only recall how slowly 
such sediments are accumulating in bays, lakes and flood-plains 
of rivers at the present time in order to form some conception of 
the immense periods of time represented by the Newark strata, 
which are probably more than two miles thick. We must further 
recognize the probability that there were long intervals during 
which deposition was retarded or possibly suspended alto- 
gether. The renewal of the soil keeps pace with the ordinary 
rate of erosion in hills and mountains of moderate slope, but the 
conglomerates of the Newark show that mountain torrents often 
rent the solid bed-rocks asunder and contributed their fragments 
in the forms of pebbles and bowlders to the accumulating sedi- 
ments. 

ORIGIN 0^ THE SEDIMENTS. 

In considering the question of origin, it is necessary to bear in 
jnind the distribution of the Newark rocks in adjoining regions 
along the Atlantic coast, as shown in Fig. i, and particularly to 
note that this belt in New Jersey is part of a long strip that 
skirts along the region of the crystalline Highlands from Haver- 
straw, New York, southwestward through New Jersey, Penn- 
sylvania, Mjaryland, and far into Virginia. This is the most ex- 



ORIGIN NEWARK ROCKS. 103 

tensive single area, but the others are much like it in form and 
characters of sediments. 

The Tidal Estuary Hypothesis, 

It has long been customary for geologists to speak of the New-' 
ark beds as having been deposited in "broad, shallow estuaries, 
whose shores were laid bare by the retreating tide, and in which 
the varying currents alternately deposited coarse and fine ma- 
terials." The ripple-marks, sun-cracks, raindrop impressions, 
and tracks of animals were regarded as proof that the strata were 
once low beaches or mud-flats, laid bare at low tide, where land 
animals came in search of food.^ "At the beginning of Newark 
time, therefore, we must conceive of a broad, shallow estuary ex- 
tending across the northern part of what is now the S'tate of New 
Jersey. * * * The streams from the bordering land areas 
carried into the estuary rock debris which was distributed over the 
bottom by the waves and tidal currents. The waves beating 
against the shore contributed their quota of material. * ♦ * 
The sudden alternation from shale to conglomerates, the rapid 
thinning out of individual layers, the presence of ripple-marks, 
raindrop impressions and mud-cracks indicate that these beds 
were formed in close proximity to the shore line. Sticks and 
trunks of trees were frequently imbedded in the layers of sand and 
gravel. These deposits were formed quite widely over the floor 
of the estuary, near the middle as well as near the present border, 
since the Hopewell and Flemington faults bring similar beds to 
the surface." * ♦ * 

"Frequent mention has been made of the fact that the Newark 
beds are shallow-water deposits throughout their entire thick- 
ness. At no time, apparently, was the water of the estuary so 
deep that the outgoing tide did not expose broad areas of sand or 
mud. It follows from this that there must have been a progres- 
sive subsidence in the estuary during the deposition of these 



*Kummel, Ann. Rep. of State Geologist, 1897, p. 139; Newberry, Mon. U. 
S. Geol. Sur., XIV, 1888, p. 5 ; Russell, Bull. U. S. Geol. Sur. No. 85, p. 45- 



I04 THE STATE GEOLOGIST. 

beds, since their thickness is to be measured by thousands of feet. 
The subsidence went on pari passu with the deposition of the 
sediments, so that the shallow water conditions prevailed con^ 
tinually," ^ 

This interpretation was regarded as satisfactory by geologists 
generally less than a decade ago, and it is still to be found in the 
current text-books. » 

The Lake Basin Hypothesis, 

In connection with the estuary hypothesis described above, or 
as an alternative to it, the supposition that some areas of Newark 
rocks were formed in lakes has been advocated. The gradual 
subsidence is assumed in this case, as in that of estuaries, and the 
concurrent filling up by sediments so as to maintain a constant 
alternation of shallow water and bare mud and sand flats. 
Otherwise the conditions of the lake hypothesis are identical with 
those stated above. , 

Objections to the Foregoing Hypotheses. 

It is now beginning to be realized ( i ) that impressions made 
on soft muds or sands at low tide are effaced by the next suc- 
ceeding high tide or are preserved only under exceptional condi- 
tions; (2) that the features once ascribed only to tidal shore, or 
littoral, deposits are much more characteristic of alluvial sedi- 
ments on land; and (3), finally, that the area of such littoral de- 
posits is much smaller than that of river-made deposits above 
tide, and that they should consequently be comparatively rare in 
the sedimentary records of the past.^ It is seen also that the 
current hypotheses offer no satisfactory explanation of the alter- 
nation of coarse sands and gravel with layers of fine mud near 
the middle as well as along the shores of the estuary or lake. 

Furthermore, the pari passu subsidence, keeping pace with the 
rate of deposition, which must be assumed in order to provide 



* Kiimmel, loc. cit, pp. 13^143. The italics are not used in the original. 

* Relative geological importance of continental, littoral and marine sedimen- 
tation. Joseph Barren, Jour. Geol., XTV, 1906, pp. 316, 430, 524. 



ORIGIN NEWARK ROCKS. 105 

continuous shallow water conditions, is highly improbable when 
extended over the immense period of time necessary for the ac- 
cumulation of sediments many thousands of feet thick. The en- 
tire absence of marine fossils ia inconsistent with the estuary- 
hypothesis, while the presence of land plants and animals, with 
only occasional fresh-water forms, is quite unfavorable to any 
extensive application of the lake hypothesis. 

These difficulties were fully realized by Professor J. D. Dana, 
who says : "It is not possible that the sandstone formation was 
made during a general submergence and in a great common body 
of water; for there is nothing marine about it in fossils or in 
structure; and fresh waters for the work could not have spread 
over the region of hills, ridges, and valleys under any probable 
circumstances.'' 

The Hypothesis of Orographic Valleys. 

Professor Dana points to the facts that the Nova Scotia and 
Connecticut Vklley belts of these rocks lie in the same troughs 
that had received sediments through a large part of Paleozoic 
time, and, further, that "the parallelism of the belts to the moun- 
tain ranges of the continental border is close,, * * * ^s 
if occupying orographic valleys of the' Appalachian mountain 
chain.'' These orographic valleys he conceives to have been oc- 
cupied by great broad rivers that made "conglomerates where 
the water had great velocity, sandstones in gentler currents, 
shales in the sluggish waters, and beds of vegetable debris for a 
coal bed where the conditions were those of a great marsh."* * * 

"Where were the sources and what the directions of the rivers 
over the higher lands from New York to North Carolina, which 
supplied so generally granitic sediments instead of quartzose 
sands and fine clays, are questions not easily answered." * * * 

"The river or waters of the time flowing southward, just west 
of the site of New York City — where now flows the Hudson — 
were 25 miles wide, as the breadth of the Triassic of the region 
shows, and they had sources evidently in the nearer mountains 
to the north, west, and south. These sources were probably in 
the Highlands and other ridges of crystalline rocks. The waters 



io6 THE STATE GEOLOGIST. 

and sediment certainly did not come from the Catskill Mountains 
to the north nor from the Alleghanies to the west/'^ 



Objections to the Orographic Valley hypothesis. 

The width of Newark strata opposite New York city is only an 
unknown fraction of their former extent, for the northwestern 
border is here determined by a fault, the Cretaceous overlaps on 
the southeast, and the monoclinal structure of the remainder 
shows that yast amounts have been removed by erosion. Assum- 
ing flood-plains of such proportions it is not remarkable that 
the sources and directions of the rivers by which they were 
formed should present difficult questions. The difficulty is vastly 
increased by the fact that the drainage of the Catskills and the 
Appalachian Mountains passed off in other directions, since the 
Newark sediments were derived from the older crystallines. 



A Piedmont Plain hypothesis. 

Four prominent conditions are to be considered in discussing 
the origin of the Newark sediments of New Jersey and the 
Atlantic region generally; namely (i) the evident derivation of 
most of the material from regions of crystalline rocks; (2) the 
strongly marked evidences of deposition by rivers, with only local 
lakes, and possibly estuaries; (3) the occurrence of these rocks 
in well-defined, long, narrow, basin-like areas parallel to the 
main structural lines of the Appalachian Mountains; (4) the 
wide-spread occurrence of fossil land plants and footprints of 
land animals, with bituminous shales in many localities and coal 
beds in Virginia and North Carolina, in contrast with the limited 
local areas of fossil fishes and crustaceans, which may be either 
brackish or fresh-water forms. 

These conditions are believed to be fully met by the hypothesis 
of river deposition across a relatively smooth piedmont plain 



* Manual of Geology, 4th ed., 1895, p. 743. 



ORIGIN NEWARK ROCKS. 107 

fronting the newly uplifted crystalline foreland, or protaxis, of 
the Appalachian Mountains, with concurrent synclinal wrinkling 
and down- faulting of the long basin-like areas in which the 
present remnants of these rocks have been preserved. 

During the Appalachian uplift and for long periods afterwards 
the crystalline protaxis must have remained the greit divide be- 
tween the waters of the Gulf drainage and those that passed 
directly into the open Atlantic. Numerous short but vigorous 
streams brought down the debris of the disintegrating and de- 
composing granites, gneisses, and metamorphic sediments of 
earlier Paleozoic age, and deposited them in coalescing alluvial 
fans across the smoother plain of the crystalline Piedmont. Oc- 
casional downward movements, of warping or faulting, gave 
opportunity for local thickening of the deposits along the belts 
affected. 

According to this conception the Piedmont plain was of much 
greater width than the present areas of the Newark strata, and 
it probably merged into coastal marine and estuarine deposits 
along the eastern border. As a rule, however, the deposits were 
probably not very thick except in the elongated areas of progres- 
sive or intermittent deformation. Hence when the whole Pied- 
mont was eventually uplifted the relatively thin mantle of debris 
was removed by erosion from the greater part of the region, and 
only those narrow belts that were protected by down-warping 
and faulting between adjacent areas of the harder crystalline 
rocks have been preserved to the present time. 

The northwestward tilting caused the displaced strata to be 
beveled off across the upturned edges and brought up again the 
crystallines along the southeastern border. These crystallines 
form the hills that everywhere skirt the eastern boundary of the 
New York- Virginia area except where it crosses New Jersey, and 
similar conditions are found in the various other belts of these 
rocks along the Atlantic slope. Across the narrowest part of 
New Jersey, however, these east^n crystallines were again so 
greatly worn down and depressed that they were buried by the 
later Cretaceous sediments, except a small area of gneisses now 
found in the vicinity of Trenton. On account of these over- 




THE STATE GEOLOGIST. 

lapping Cretaceous sands and clays, the exact southeastern limit 
of the Newark formation from Trenton to Staten Island is not 
known. 

The generally scant vegetation and the highly oxidized, iron- 
stained sediments that prevail in the Newark strata strongly sug- 
gest an arid climate. In this case the deposition of the sediments 
was perhaps as much due to loss of volume as to change of slope 
in the contributing' streams, as in the arid piedmont plains of 
southern California and elsewhere in the western United States 
to-day. 

Late in the period of deposition of the Newark strata con- 
tinued depression of the elongated narrow belts along the Pied- 
mont plain, by folding and faulting, eventually gave rise to 
fissures through which repeated eruptions of lava overspread 
considerable areas of the deposits and great intrusive sheets, or 
sills, of similar lava were injected between some of the deeply 
buried strata. 

GEOI.OGIC REI.ATI0NS OV^ THE TRAP ROCKS. 

The distribution of the trap rocks, which constitute more than 
one-tenth of the total Newark area of the State, is shown on the 
accompanying map, PI. XXVIII. Davis, Darton, Kiimmel and 
other workers in this field have shown that these rocks are of 
igneous origin and were formed during the latter part of Newark 
time. They represent both lavas that reached the surface and 
became extrusive^ and also lavas that penetrated the sediments 
and became intrusive. Their geologic relations have been de- 
scribed in detail by Kiimmel in a previous report of the Sur- 
vey.^ Supplementary to that report, attention is here directed 
to certain further correlations of the various trap masses and 
to some difference of interpretation of observed relations. 

Relations of the Extrusives, 

The Watchung flows. — The Watchung Mountains and the 
various trap ridges west of them are all extrusive sheets, or lava 



'Ann. Rep. State Geologist of N. J. for 1897, pp. 58-99- 



ORIGIN NEWARK ROCKS. 109 

flows, as are also the semi-circular ridges near New German- 
town and Sand Brook. The grouping of these sheets in the 
west-central portion of the area, where no intrusives occur, and 
their almost total absence from the areas of intrusives to the 
northeast and southwest are characteristics which are forcibly- 
impressed by the map, PI. XXVIII. The former is the area of 
uppermost and, therefore, latest Newark strata, while the deep- 
seated intrusive masses have been laid bare only where these later 
strata have been removed to great depths by erosion. 

The thinning out of the lowest extrusive lava sheet north of 
Somerville apparently causes the narrowing down of First 
Mountain and its final termination at Pluckamin. Second Moun- 
tain recurves in hook form until cut diagonally across by the 
great boundary fault near Bernardsville. This fault continues 
northward to the State line and terminates the curved extremities 
of all three of the extrusive sheets beyond Pompton. The re- 
curved ends of these ridges are the result of the Passaic Basin 
syncline, the shallow boat-like structure into which the strata 
and the trap sheets of this region have been bent. 

Packanack and Hook mountains, Riker Hill and Long Hill, 
by their structure and attitude with reference to each other, are 
quite probably parts of a single extrusive sheet. As to their ex- 
trusive character there can be no question, and they are all much 
thinner than the great flows that constitute First and Second 
mountains. Their disconnected character may be explained 
upon the hypothesis that the eruption was slight and did not com- 
pletely cover the area, .so that there were tongues, or project- 
ing lobes of lava, or there may have been several small eruptions 
from independent vents or fissures. On the other hand, tKeir dis- 
continuity may be due to preglacial or glacial erosion, the por- 
tions that were most worn down being buried by the later de- 
position of glacial drift and river sediment that now cover much 
of this region. 

All of these hypotheses seem to be consistent with the facts 
so far as known, but further knowledge of the strata now buried 
beneath the broad alluvial flood-plains of the upper Passaic River 
may be necessary in order to determine which is the correct in- 

8 GEOL 



no THE STATE GEOLOGIST. 

terpretation. Under the circumstances, one of the hypotheses of 
scant eruption seems most probable. 

The semi-circular trap ridge near New Vernon is a thin extru- 
sive sheet exactly similar to that of Long Hill; and, in fact, 
it seems quite certainly to be the upturned western border of the 
same sheet. The structure of the shales within the trap ridg^ 
shows that it has been brought up by a dome-like anticline, or 
upward fold, which has thrown the outcrop far enough eastward 
to prevent its being cut off by the great fault along the adjacent 
border of the crystalline Highlands. 

The Double Crest of Second Mountain, — The striking and per- 
sistent double crest of the curved southwestern part of Second 
Mountain (Fig. 2) has been explained^ as the result of a curved 
longitudinal fault parallel to the present outcrop of the trap sheet. 
While entirely consistent with the facts so far as at present 
known, the probability of such a coincidence is so extremely 
small that, in the absence of positive proof of faulting, this 
hypothesis must be regarded as exceedingly doubtful. Brief dis- 
cussions are here given of (i) the facts requiring explanation, 
(2) the interbedded shale hypothesis, (3) the curved longitudinal 
fault hypothesis, and (4) the hypothesis here advanced, namely, 
that of a double flow of lava with intercurrent warping. The last 
is somewhat more fully presented and its bearing upon subsequent 
geologic history discussed. The others are summarized from 
Kiimmel's report, above cited. 

(i) The facts requiring explanation. — ^The width of outcrop 
of the trap along Second Mountain varies greatly. The hook- 
shaped southwestern portion is broader than elsewhere, and for 
a distance of 17 miles the crest is distinctly double. In the 
intervening valley shale has been found in a number of places, 
either in well-borings or at the surface. At both ends of the 
ridge, however, the crest is single, and no shales are found inter- 
bedded in the trap in the gorge of the Passaic River at Little 
Falls. In a well at Mount St. Dominic Academy, at Caldwell, 
the following section was found: Glacial drift, 100 feet; trap 



^Darton, Bull. U. S. Geol. Survey No. 67, p. 22. Kummel, Ann. Rept. of 
State Geologist for 1897, p. 125. 



ORIGIN NEWARK ROCKS. 



Ill 



rock, 775 feet ; total 875 feet ; shale at the bottom. A well bored 
for Mr. KeanQ on the inner crest of Second Mountain, near East 
Livingston, and 3 miles from the well at Caldwell, furnished 







the following section: Soil, 5 feet; trap rock, 90 feet: brown 
sandstone, 51 feet; trap rock, 381 feet; total, 527 feet. Both 
wells are in such locations as to pass through an interbedded 



112 THE STATE . GEOLOGIST. 

layer of sediments, if such existed. Over the country between the 
two crests, Darton found red shale fragments, which he regarded 
as portions of underlying sediments. 

(2)"-The-4nterbed<ied shale hypothesis. — Kiimmel considered 
the hypothesis that Second Mountain is composed of two succes- 
sive flows of lava separated by a continuous stratum of sediments, 
but rejected it for the following reasons: (a) the crest is single 
at both ends of the ridge; (b) no trace of shale is found at either 
locality; (c) the Little Falls gorge and the Caldwell well show 
no shale. The "brown sandstone" reported from Mr. Keane's 
well he regards as probably a red-brown variety of trap. 

(3) The fault hypothesis. — Under the apparent necessity of 
choosing between the interbedded shale hypothesis, described 
above, and that of a f^ult which conforms to the present outcrop 
around the sharply recurved southwestern extremity of Second 
Mountain, both Darton and Kiimmel adopted thejatter, in spite 
of the fact that "no direct evidence of faulting beyond that 
furnished by the topography — the- repetition of the beds — ^was 
found." "Indirect evidence derived from a study of the width 
of the outcrop of the trap and the apparent thickness along dif- 
ferent section lines," may be summarized as follows : On the as- 
sumptions (a) that there was no deformation in the intervals 
between the lava flows (nor accompanying the flows) ; (b) that 
sedimentation was uniform throughout the area; and (c) that 
the lava sheets are approximately of uniform thickness, their 
bases must have been originally parallel. Allowing for known 
faults this is still true of First and Second mountains ; but from 
the base of the Second to that of the Third (Long Hill, etc.), is 
a distance that varies greatly in different sections, and the ap- 
parent differences are greater where the double crests of Second 
Mountain are most marked. This variation is ascribed to fault- 
ing, which Darton assumed further to be confined to the present 
areas of trap outcrop. 

Kiimmel points out several very obvious defects in the above 
reasoning: (i) that any or all of these varidus assumptions 
may be incorrect; (2) that there is no conclusive reason for sup- 
posing that faulting is restricted to the trap areas of the present 



ORIGIN NEWARK ROCKS. 113 

surface, and (3) that variations in thickness of either the trap, 
of Second Mountain or of the overlying shales would vitiate the 
conclusions. Notwithstanding these elements of uncertainty and 
improbability, however, the estimates based on the above assump- 
tions are regarded as "indicating quite clearly that some faulting 
has occurred," and as "strengthening the argument derived from 
the double crest." Hence the conclusion that "it is safe to assume 
that Second Mountain is traversed for much of its extent by a 
curving longitudinal fault." 

(4) A hypothesis of double flow with intercurrent warping. — 
The explanation here advanced is believed to be consistent with 
all the known facts and to involve no improbable assumptions. 
It is practically the interbedded shale hypothesis, described above, 
freed from the restrictions of stability and uniform sedimentation 
in the intervals between the lava flows. 

The present condition of the Newark rocks throughout eastern 
North America shows that they have been subjected to univers«nl 
deformation, and as yet there is no known means of defining the 
exact stage in their history at which the disturbing movements 
began. The slightest warping of the surface at any stage of the 
sedimentation would have its inevitable effect on the thickness 
and distribution of the subsequent deposits. This is specially true 
of shallow water and continental formations, such as these 
Newark beds are generally conceded to be. 

The proposed hypothesis to account for the conditions abo\^ 
enumerated in Second Mountain may be stated as follows : After 
the eruption of the First Mountain trap sheet and the deposition 
of some 600 feet of overlying shales and sandstones, a second 
eruption occurred, forming a lava sheet averaging probably 500 
feet thick over the same region. With this outflow began a 
gradual depression of the southern axial region of the Passaic 
Basin syncline — the region from Somerville northeastward. As 
a result subsequent deposits were concentrated in this region, 
tending to build it up to the level of the adjoining area, but not 
succeeding entirely in this before deposition was again ipter- 
rupted by eruption. Another lava sheet of about 500 feet average 
thickness was spread over the region, but not uniformly, nor even 



114 THE STATE GEOLOGIST. 

approximately so, as the preceding flow had been. Over the 
shales in the depressed area the maximum thickness was at least 
800 feet, while in the adjoining- r^ons where it rested on the 



unburied flanks of the previous flow it did not exceed 200 feet. 
Thus the two flows merged into one on the sides of the incipient 



ORIGIN NEWARK ROCKS. 115 

syncline, but were separated by a thin stratum of shale in the 
depression. (Figs. 3 and 4). 




fig. 4. 

Sediments. Trap sheets. 

Cross section on line A-B, figure 3. 

When the edges were later upturned to the forces of weather- 
ing and erosion the soft shales quickly wore away to a lower level, 
thus forming the continuous valley curving conformably with 
the outcropping edges of the adjacent traps above and below. 
The valley between the double crests of Second Mountain is, 
therefore, considered to be exactly comparable to Washington 
Valley between First and Second mountains. It is shallower and 
the escarpment of the overlying trap outcrop is less pronounced 
because of the limited thickness of the interbedded shales. 

(Figf. 4). 
Evidence of continued depression in the same synclinal region 

is found in the sediments between Second Mountain and the over- 
lying trap sheet of Long Hilll. There is a decrease of one-fourth 
in the thickness of the intervening shales at Madison as compared 
with those at Millington, and a much more rapid thinning out 
toward the west. The trap sheet of Long Hill is also thicker 
about Millington, but this may not be due to original inequality 
of the surface upon which it was laid. 

The Sand Brook and New Germantown Bxtrusives. — ^These 
two small areas deserve special notice, because they have pre- 
served remnants of trap sheets that were doubtless once much 
more extensive. Eiach is but the eastern spoon-shaped end of a 
syncline that has been cut off by a fault to the west, and each con- 
tains remnants of two separate masses of trap of exactly similar 
forms and relations. The larger mass in each case outcrops in a 
westward-pointing crescent and curves downward beneath the 
shales within. The smaller caps a rounded hill between the 
points of the crescent, thus resting upon the sediments that overlie 



ii6 THE STATE GEOLOGIST. 

the synclinal sheet below. ^ At New Germantown this upper 
fragment is separated, doubtless by erosion, into two small dis- 
connected masses. 

Here we have remnants of two lava flows, separated by several 
hundred feet of shales, in exactly the same manner as the sheets 
of the Watchung Mountains. Kiimmel^ has shown, from the 
structure of the region, that they are "in a general way contem- 
poraneous with the Watchunjg flows," but concludes that "there 
is no evidence that they are parts of the same flows." It may also 
be stated, on the other hand, that there is no evidence that they re- 
present separate flows, and it may be shown that they probably 
do not. The lava sheets whose eroded edges form First and 
Second mountains, are certainly only remnants of the original 
flows, yet they still occupy a region about 12 by 40 miles in* extent. 
Considering their great thickness in the vicinity of Bound Brook 
and Somerville, it is altogether probable that they once extended 
half as far again to the southwest, which would carry them be- 
yond the most distant remnants at Sand Brook. In this case rem- 
nants of the eroded Watchung sheets, if of earlier origin, would 
now underlie those of New Germantown and Sand Brook, and 
would outcrop in larger curves to the east of these localities. On 
the other hand, unless these small remnants are parts of very 
limited local flows, they would also have overlapped the present 
area of the Watchung sheets. This is especially true of the New 
Germantown trap, which is only 6 miles distant. In this case their 
edges would appear in the shales beneath and southeast of the 
Watchung ridges, if older, or above, in the Passaic Basin syn- 
cline, if younger. 

Since it is clear, then, from the stratigraphy of the region, that 
the New Germantown and Sand Brook traps are approximately 



^ Kiimmel, finding the contacts of these small . inner trap masses so ob- 
scured by soil-covering at both localities that their relations to the sediments 
could not be observed, did not commit himself as to their extrusive or intru- 
sive character. (Ann. Rep. of State Geologist of N. J., 1896, 1897.) The 
absence of metamorphism in the shales was noted, however, and the trap 
is quite vesicular, so that there can be little doubt that the interpretation 
given above is correct. 

'Ann. Report of State Geologist of N. J., 1897, p. 98. 



ORIGIN NEWARK ROCKS. 117 

contemporaneous with the Watchtmg flows, the conclusion is al- 
most imperative either ( i ) that they are exactly contemporaneous 
and parts of the same sheets, or (2) that the present remnants 
are fragments of small local outpourings of earlier date than the 
Watchung flows. Of these the former conclusion seems the more 
probable, and on this basis the New Germantown and Sand 
Brook traps are correlated with the trap sheets of First and 
Second mountains. 

It should not be overlooked, however, that there is still another 
possible interpretation, namely, that neither the New German- 
town and Sand Brook traps, on the one hand, nor the trap sheets 
of the Watchungs, on the other, have ever extended far enough 
beyond their present boundaries to overlap the regions now 
occupied by the other. In this case their relationships can be 
-established only by the stratigraphy ; and it is impossible, in the 
bomogeneous red Brunswick shales of this region, to attain more 
than an approximate correlation, as quoted above from Kiimmel. 
Even in this case, however, it is more probable, a priori, that the 
smaller eruptions took place contemporaneously with the greater 
volcanic activity in the adjacent area than at other times. 

Relations of the Intrusives, 

The sills, or intrusive sheets, include the Palisades to the 
northeast, along the Hudson River, and the trap ridges of Rocky 
Hill and of Pennington, Baldpate, Sourland, and Cushetunk 
mountains in the southwestern part of the area. Other intrusive 
masses, often closely associated with these, are more of the na- 
ture of round bosses, such as Mount Gilboa and the Snake Hills, 
or in the form of thin dikes, like that which crosses the Mill- 
stone River west of New Brunswick, and numerous shorter ones 
in other localities. 

The Palisades, Rocky Hill, Sourland Mountain, Byram. — Both 
the position and direction of the main outcrop of the Rocky Hill 
trap strongly suggest that it is a continuation of the Palisades 
sill, as pointed* out by various former observers. Darton^ 



*Bull. U. S. Geol. Survey, No. 67, 1890, p. 39. 



ii8 THE STATE GEOLOGIST. 

states that "the interval between the Staten Island outcrops and 
those at Lawrence Brook is mostly covered by Cretaceous clays, 
under which the Newark is known to extend for some distance, 
and it is possible that the trap continues southward and is simi- 
larly overlapped." A number of facts that have been gathered 
from deep-well borings and river dredging in the intervening ter- 
ritory now make it practically certain that this supposition is 
true. (See PI. XXIX.) 

On Staten Island, shallow wells show the continuation of the 
Palisades sill southward to the vicinity of Fresh Kills, opposite 
Carteret, New Jersey. Three wells at the car works near Car- 
teret (a, PI. XXIX), after passing through sand and' clay 60 and 
90 feet, respectively, struck hard rock that "dulled the drill in 15 
minutes," and reported by the contractor as "evidently trap 
rock."^ At Boynton Beach (b, PL XXIX), 3 miles southwest- 
ward, the following well-section was found: 

Clay, sand and gravel, 75 feet. 

Red shale, 3 " 

Trap rock, 70 " 

Red sandstone, 2 " 

Trap rock, 7 " 

Total, 157 " 

Evidently a sandstone inclusion in the trap was here en- 
countered, similar to those found at numerous points northward 
along the Palisades.^ Two wells bored at Maurer station (c, d, 
PI. XXIX), 2 miles north of Perth Amboy, found trap under 
sand and clay 64 feet and 78 feet deep, respectively.^ In a well 
drilled at M. D. Valentine & Brothers Company's works, three- 
fourths of a mile south of Woodbridge {e, PI. XXIX), at a depth 
of 56 feet hard rock was found. At first this was supposed to be 
trap, but it afterwards proved to be indurated shale and sand- 
stone. These are undoubtedly the metamorphic sediments over- 



■Ann. Rep. State Geologist of N. J. for 1896, p. 199. 

•Ann. Rep. State Geologist of N. J. for 1904, p. 265. 

'Ann. Rep. State Geologist of N. J. for 1904, p. 268; 1895, p. 93. 



ORIGIN NEWARK ROCKS. 119 

lying the trap silL^ Near Keasby (/, PI. XXIX), on the Rari- 
tan River, 2 miles west of Perth Amboy, hard rock, probably 
trap, was encountered under 72 feet of sand and clay.^ 

In dredging- and blasting operations in the Raritan River, a 
mile below Martins Dock (g, PI. XXIX), a reef of indurated 
shale 500 feet wide was found crossing the river in a northeast- 
southwest course, 5 to 12 feet below low water. No trap rock 
was found, but it cannot be doubted that this shale corresponds 
to the belt of metamorphic sediments everywhere skirting the 
great intrusive sills of trap.^ Also 2 miles southeast of Deans 
station (A, PI. XXIX), on the Pennsylvania Railroad, near Fresh 
Ponds, a bored well encountered trap rock under 60 feet of clay, 
unquestionably the buried margin of the Rocky Hill mass, which 
outcrops about Deans. ^ 

Mr. W. R. Osborne, the contractor, also reports that trap was 
encountered in a bored well near the old Baptist church at South 
River, at a depth of 130 feet. 

The trap dikes east, south and west of New Brunswick bear 
about the same relation to this buried extension of the Palisades 
sill as do those of the Snake Hills, Arlington, Granton and Bo- 
gota to its prominent outcrop farther northward. (Pls.XXVIII 
and XXIX.) As pointed out in the discussion of the copper ores, 
those of New Brunswick and Newtown occupy the same relative 
position with reference to this covered part of the sill that the 
ores of Arlington and Glen Ridge hold with regard to the 
Palisades. 

The Palisades trap lies much lower in the sedimentary series 
than that of Rocky Hill, but the latter is highest at its western 
extremity and rapidly descends to lower horizons to the east, 
where it finally passes under the Cretaceous cover. A continued 
drop would readily unite it with the Palisades sill on Staten 
Island. Furthermore, the Rocky Hill trap increases in thickness 



^Ann. Rep. State Geologist of N. J. for 1895, p. 93. This locality was 
erroneously reported as i54 miles southwest of Woodbridge. 
'Ann. Rep. State Geologist of N. J. for 1898, pp. 131, 132. 
"Ann. Rep. State Geologist of N. J. for 1882, p. 59; 1895, p. 93. 
*Ann. Rep. State Geologist of N. J. for 1900, p. 159. 



I20 THE STATE GEOLOGIST. 

eastward from its narrow outcrop near Hopewdl, and the same 
thickening is continued in the Palisades sill northward from 
Staten Island and Bergen Point. As it passes further northward 
into New York the Palisades trap again becomes thinner, and its 
recurved extremity rises rapidly through the sediments west of 
Haverstraw until it reaches almost the top of the series. Their 
relations to the sediments are, therefore, entirely consistent with 
their continuity. 

The intrusive trap masses of Pennington and Baldpate moun- 
tains are doubtless lobe-like protrusions of the same Palisades- 
Rocky Hill sill, as suggested by Darton, and all probably merge 
into one continuous sheet at no great depth. The irregular forms 
of Pennington and Baldpate mountains and the northeastward 
arm of Rocky Hill all indicate subterranean branching of the in- 
trusive lava in this region. 

The relations of the Sourland Mountain trap, brought up by 
the Hopewell fault in a repeated series of strata dipping north- 
westward, strongly suggest that it is also a part of the Palisades- 
Rocky Hill sill. (See section, PI. XXVIII. ). If depressed some 
6,000 feet, the approximate throw of the fault, it would fall into 
line with the subterranean continuation of the trap of Rocky Hill, 
Pennington Mountain and Baldpate Mountain. In a similar 
manner Mount Gilboa, above Lambertville, and the smaller iso- 
lated trap mass at Byram, each lying on the upthrow side of a 
fault that repeats a portion of the sedim.entary series, may reason- 
ably be regarded as fragments of the same sill brought up from 
near its thinner northwestern border. 

Thus, according to the view here advocated, the intrusive trap 
masses outcropping in the Palisades, in Rocky Hill, in Penning- 
ton, Baldpate and Sourland mountains, in Mount Gilboa, as well 
as the mass at Byram, are all to be regarded as probably parts 
of one continuous intrusion, separated by the Cretaceous overlap 
in the case of the Palisades and Rocky Hill, by lobe-like subter- 
ranean branching in Pennington and Baldpate mountains, and 
by faulting in the other cases. 

There is a widespread impression that the Palisades sill drops 
steeply downward across the strata from its western margin, and 
geologists have generally so represented it in cross-sections. This 



ORIGIN NEWARK ROCKS. 121 

impression is doubtless due to the preponderating influence of 
three easily accessible upper contacts that do show such conditions 
for 20 or 30 feet. These are in the West Shore and N. Y. S. & 
W. Railroad tunnels through the Palisades, and the West Shore 
tunnel near Haverstraw. In two of these localities (the West 
Shore tunnels) both the topography and the boundaries of the 
trap outcrop show clearly that the relations are exceptional ; but 
they have been emphasized by detailed descriptions and illustra- 
tions in the reports, while the conformable contacts have very 
naturally been passed over with a simple statement of the facts. 

Kiimmel^ has described four conformable upper contacts, two 
unconformable, and two doubtful, while of the under contacts 
along the Hudson River only three are conformable, fifteen are 
unconformable, and one is doubtful. Yet, in spite of the numer- 
ous irregularities of the under surface of the trap, and its con- 
stant shifting from one horizon to another, it is evident that in 
a broad general view it is approximately conformable to the 
sedimentary strata. Even less irregularity is known in its upper 
surface, but probably, if an equal number of contacts could be 
observed, the conditions would be found about the same. At 
any rate, there seems to be no good reason why these upper con- 
tacts should be regarded as showing the -fissure arising from the 
deep-seated origin of the lava, when it is perfectly clear that simi- 
lar contacts beneath the Palisades are not susceptible of such 
interpretation. 

Off-shoots of the Palisades SilL — Snake Hill and Little Snake 
Hill are two knobs of trap which stand up prominently out of 
the Hackensack Meadows at distances of a mile and three-eighths 
and I mile, respectively, from the foot of the western slope of 
the Palisades. If the Palisades trap continues approximately con- 
formable to the sedimentaries under the meadows, as it does 
along the Hudson River, it probably does not lie more than 1,600 
feet and 1,300 feet, respectively, below the outcrops of the Snake 
Hills. These have, therefore, been very naturally regarded as 
off-shoots from it. In other words, they are less than one-fourth 
as far from the underlying sill as from its nearest outcrop, and it 



*Ann. Rep. State .Geologist for 1897, pp. 62-72. 



122 THE STATE GEOLOGIST. 

would be difficult to construct.a section on the basis of our present 
knowledge without connecting them with the Palisades. 

The trap dike and sheet that form the small hill just north of 
Granton are about 800 feet from the nearest outcrop of the 
Palisades trap, but they cannot be more than 200 feet above the 
underlying portion of it. They must also be regarded, therefore, 
as an off-shoot from the Palisades. 

The dikes and sheets at the Arlington copper mine are 4 miles 
from the Palisades at Jersey City and 6 miles from the trap of 
First" Mountain at Montclair. Since the latter is a perfectly con- 
formable sheet, dipping westward with the sedimentaries on 
which it rests, and the former is approximately conformable, with 
a similar dip, it seems probable that these dikes are also off-shoots 
of the Palisades sheet, which, with an average westerly dip of 
12 degrees, would lie some 8,000 feet below. 

In like manner the dike at Bogota, the numerous dikes east, 
•south, and west of New Brunswick, and those scattered over the 
region northwest of Sourland Mountain are most readily ex- 
plained as thin off-shoots from the same sill. In fact some of 
these in the last-named area have been traced by Kiimmel to a 
direct connection with the great intrusive sheet at the outcrop, 
and there is little room to question that the others are of the same 
character. 

Cushetunk and Round mountains, — The trap masses of Cush- 
'Ctunk Mountain and Round Mountain are intrusives of the same 
character as the great Palisades-Rocky Hill-Sourland Moun- 
tain sill, and may represent a contemporaneous upward protrusion 
of the same magna, but there is no means of definitely determin- 
ing this question. There is, however, an interval of little more 
than 3 miles between Round Mountain and the dikes about 
Flemington, which are undoubtedly offshoots of the Sourland 
Mountain trap. Whether belonging to the same period of in- 
trusion as these or not, it does not seem improbable that the up- 
ward movement of the magma was stopped and possibly its 
lateral extension determined by the overlying extrusives of the 
Watchung Mountains which have since been removed . from this 
region by erosion. It is shown, in discussing the relations of 
the New Germantown and Sand Brook synclines, that the trap 



ORIGIN NEWARK ROCKS. 123 

sheets of First and Second mountains probably once extended 
over this region, and the known structures would carry them 
across just over Cushetunk Mountain. 

The mutual relations of the various disconnected outcrops 
about Cushetunk and Round mountains are open to question. 
The structure is complicated and there are not sufficient outcrops 
of the sedimentary strata available in the vicinity of the trap 
masses to make satisfactory conclusions possible — ^not at least 
without considerably more minute and painstaking search over 
the area than it has yet been possible to make. Darton^ concluded 
that all the masses in this vicinity had once probably constituted 
one wide intrusive sheet, "considerably flexed, and with the 
form of its present outcrops mainly determined by the removal of 
the trap from the crests of the anticlinals.'' Kiimmel,^ on the 
other hand, after thorough examination of the surrounding sedi- 
mentaries, concluded that the curving outline of Cushetunk 
Mountain "is not due, primarily, at least, to an anticlinal or syn- 
clinal fold in the shales, but to the curving fracture through which 
the trap has come.'' As to Round Mountain, he thought it prob- 
ably intrusive, but did not regard the evidence as complete as in 
the case of Cushetunk Mountain. Metamorphic effects observed 
in the sediments on the slopes of the mountain in this investiga- 
tion leave no doubt as to the intrusive character of the 
adjacent trap, and this is in harmony with its prevailingly coarse 
granitic texture. As to the relations of Round Mountain, the few 
facts observed seem to favor Darton's conclusion that it "lies in a 
well-defined synclinal or spoon, and is separated from Cushetunk 
by a local anticlinar' from which the trap has been removed by 
erosion. 

Origin of the Trap Rocks. 

The following statements in regard to their origin, while fol- 
lowing in the main the conclusions of previous investigators, 
differ in some important details, particularly as regards the char- 
acter of Second Mountain and the conditions of intrusion. 



* Bulletin U. S. Geological Survey No. 67, p. 64. 

' Annual Report of the State Geologist for 1897, p. 76. 



124 THE STATE GEOLOGIST. 

Origin of the First Mountain Extrusive, 

Eventually when weighed down under some 10,000 feet of 
clays and sands, in the New Jersey region, continued subsidence 
along the narrow belts of the Piedmont resulted in deep-seated 
fractures through which a great flood of lava was forced up. 
Breaking its way through the weak layers of the overlying sedi- 
ments it spread in a broad sheet about 600 feet thick over the 
area of the present Watchung Mountains and beyond. How far 
beyond there is no present means of estimating. A remnant of 
this sheet remains, and its outcropping edge, now tilted up and 
worn by long erosion, forms First Mountain. Following this 
eruption, deposition and depression continued as before through 
a long period of quiet, during which the great lava sheet was 
buried under about 600 feet of additional sediments. 



Origin of the Double Flow of Second Mountain, 

Again the trough-like belt of depression was fissured and an- 
other flow of lava followed, forming a sheet of about 500 feet 
in average thickness. 

The beginning of the great Passaic Basin syncline of the 
Watchung Mountain region probably dates from this period. 
The first gentle sagging was chiefly confined to the southeastern 
area of the, Watchungs, in the region northeastward from Bound 
Brook. Consequently subsequent sediments were somewhat 
concentrated in' this region tending to keep it graded up to the 
level of the surrounding area; but sedimentation was locally ex- 
ceeded by depression, and possibly a lake was formed here, until 
the slow and gradual processes of deposition were again violently 
interrupted by eruption. Upon the thin blanket of sediment, 
I)erhaps less than 50 feet thick in the synclinal axis, and over the 
adjoining bare areas of the preceding flow, another lava sheet 
was spread with an average thickness of about 500 feet. Un- 
like the preceding flows, this was not even approximately uni- 
form in thickness. In the more depressed synclinal area the 



ORIGIN NEWARK ROCKS. 125 

maximum thickness was at least 800 feet, while on the flanking 
bare areas of the preceding flow it did not exceed 200 feet. Thus 
the great double sheet of trap, now tilted up and outcropping in 
Second Mountain, is separated by a thin deposit of shale in the 
synclinal axis ; hence the notable double crest around its curved 
southwestern extremity.^ 

Continued gentle sagging of the newly formed Passaic Basin 
syncline again caused increased thickness of the overwashed sedi- 
ment in the central areas during the long period of quiet deposi- 
tion that followed. 

Origin of the Long Hill Bxtry^ive, 

The great double sheet of Second Mountain was buried be- 
neath 1,500 to 2,000 feet of mud, when occurred the fourth, and, 
so far as the records preserved to us show, the last interruption 
of quiet deposition by renewed igneous activity. This final out- 
pouring was small as contrasted with the enormous flows that 
preceded it. Its average thickness was probably not over 300 
feet, and it apparently did not completely cover the area within 
the present basin of the upper Passaic River. Its irregular 
lobes may account for the present disconnected outcrops about 
New Vernon, and in Long Hill, Riker Hill, Hook and Packanack 
mountains. On the other hand, these may be the result of small 
local lava flows through several independent vents. 

Finally the red shales overlying this last trap sheet, and now 
underlying the glacial drift and the recent river and meadow ac- 
cumulations of the upper Passaic Basin, were gradually deposited 
in.the uneventful period that followed the last volcanic outburst. 

Origin of the Intrusive Trap Masses, 

As to Kummel's conclusion that the great intrusive traps were 
formed late- in Newark time there can be no question, since sev- 
eral of the masses penetrate rocks that lie far above the middle of 



* This double crest of Second Mountain has heretofore been explained upon 
the hypothesis of a "curved longitudinal fault." A discussion of this 
hypothesis will be found on page 112. 

9 GEOL 



126 THE STATE GEOLOGIST. 

the series. He further states^ that "there are good reasons for 
believing that many, probably all, of the intrusive sheets are 
younger than the extrusive, although the evidence is not con- 
clusive," and suggests that intrusive sheets may have been 
formed only after the overlying sediments became so thick that 
the lava could not readily rise to the surface. According to any 
theory of deposition, however, the elevation of the surface did 
not vary greatly during the whole of Newark time. The force 
necessary to lift the lava to the surface would be little greater, 
therefore, at the close of deposition than at the beginning. , 

It is quite probable, however, that many of the deeper-lying 
strata had become appreciably consolidated by the close of the 
I)eriod, and that the several extrusive lava sheets now included 
in the series formed an additional barrier against further erup- 
tion. But inherent in the nature of the rocks themselves there 
was also a strong tendency to intrusion. The specific gravity 
of the trap averages about 3.0, while that of the sediments is ap- 
proximately 2.5. Thus for every hundred feet in height of a 
column of lava there is an excess pressure of about 20 pounds per 
square inch over that of the inclosing strata. In case of such 
lava forced to the surface through 12,000 feet of sediments, the 
difference in pressure is 2,400 pounds per square inch at the bot- 
tom of the series. This is the measure of the tendency to intru- 
sion. A standing column of such material, if it could be main- 
tained in a liquid state would all find its way into the lower 
strata, lifting the overlying beds upon its surface. A gentle 
welling up of lava under such conditions, if it ever occurred, 
would necessarily result chiefly in intrusive masses. The over- 
flow, then, is roughly a measure of the force of eruption in px- 
cess of that required merely to lift the lava to the surface. 

Since cohesion in unmetamorphosed strata is always less along 
the bedding-planes than across them, solidification, in whatever 
degree, would also favor intrusion, unless the eruption followed 
a previously formed fissure. In the latter case the reverse would 
be true. The progressive consolidation of the sediments, there- 
fore, and the resistance of the great lava sheets already imbedded 



* Ann. Report of State Geologist of New Jersey 1897, p. 99. 



ORIGIN NEWARK ROCKS. 127 

in the upper strata would furnish predisposing conditions which 
might divert an eruption of considerable violence into subter- 
ranean channels. Hence it is altogether probable that the prin- 
cipal intrusive bodies were formed after the surface flows, and 
possibly in the early stages of those disturbances that put an end 
to deposition and eventually led to the deformation of the whole 
series by elevation, folding, and faulting. 



DEFORMATION AND EROSION. 

The folding and. faulting to which both the sedimentary and 
igneous rocks have been subjected were occasioned to some ex- 
tent by the subsidence of the Piedmont region during the accum- 
ulation of the sediments, but much more by the uplift that re- 
versed the direction of moveijient, raised the whole formation, 
and gently tilted it to the northwest. In some places the strata 
were wrinkled into low folds, and two great faults displaced 
the central portions in the southwestern part of the New Jersey 
. area. Other faults are found to determine the greater portion 
of the northwestern boundary, and numerous smaller ones occur 
throughout the region. The boundary faults belong to the pre- 
ceding period of depression, and possibly some of the others also 
date their beginnings from that i)eriod. 

It is a point worthy of note that, almost without exception, the 
known faults of the Newark strata in New Jersey have, the down- 
ward displacement on the southeast side and the up-throw on the 
northwest side of the fissure. Bearing in mind the further fact 
that the sandstones and shales of this series usually dip north- 
westward from 10 to 15 degrees in quite a regular monocline, 
it is readily understood how the great Hopewell and Flemington 
faults of the southwest (PI. XXVIII), involving displacements 
of many thousands of feet, have caused a threefold repetition of 
the stata and their included trap sheets along the Delaware River 
above Trenton. Thus at least half of the great width of the 
Newark belt in that region is due to this repetition of the series 
by faulting. 

No such great faults are known in the central and northeast- 
em parts of the belt, but displacements of smaller amounts, 



128 THE STATE GEOLOGIST. 

ranging from less than a foot to several hundred feet, are fre- 
quent in the trap sheets of the Palisades and the Watchung 
Mountains ; and occasionally in fresh exposures of the rocks, 
similar faults are observed in the sediments. The monotonous 
uniformity of the shales and the sandstones, however, renders 
the detection of such faults well nigh impossible under ordinary 
conditions, apart from the trap sheets. Under the very prob- 
able assumption that the intervening areas are as greatly affected 
in proportion as the trap outrops, it will be seen that no incon- 
siderable fraction of the width in the central and northeastern 
portions of the Newark area is probably due to repetition on a 
small scale by numerous faults. 

These movements of faulting and folding, together with the 
enormous erosion which the entire region has since undergone, 
have been the determining causes of the present topography, 
particularly the altitude and location of the trap ridges. The 
causes of these movements have been fully discussed by previous 
writers.^ 

The Supposed Fault Along the Hudson River. 

It has been often supposed that the southeastern boundary of 
the Newark along the Hudson River has been determined by a 
fault, and that in a measure this fault has influenced the lower 
course of the river. The existence of such a fault has not been 
fully established, however, since very little is known of the 
nature of the contact between the Newark strata and the crystal- 
line foundation on which they rest. Several deep wells in Ho- 
boken, Jersey City, and Bayonne^ that have penetrated from 
I, GOG to 2,000 feet of sandstone very near the border seem to 
lend support to the fault hypothesis ; but in all cases these may 
also be explained as normal overlaps with the Newark strata 
dipping 15 to 20 degrees to the west. 



^Davis, 7th Ann. Rep. U. S. Geol. Survey, pp. 484-487- See also i8th Ann. 
Rep. U. S. Gcol. Survey, p. 140; Ann. Rep. State Geologist of N. J. for 1897,, 
p. 146. 

'Ann Rep. State Geologist of N. J. 1882, p. 140; 1898, p. 139; 1904, pp. 
264, 266. 



ORIGIN NEWARK ROCKS. 129 

Neither is it necessary to suppose an intervening fault in order 
to explain the contraposition of the Palisades with their under- 
lying shales and sandstones on one side of the river and the 
prominent hills of crystalline rocks on the other. The projec- 
tion of the lowest strata across the Hudson with a dip much less 
than the average in this vicinity would carry them well over the 
tops of the opposite hills. In fact the characters of both the 
sediments and the trap of the Palisades make it quite certain that 
these rocks once extended considerably further northeastward 
than their present limits; and from, the theory of continental 
origin of the sediments here advocated it is not at all improbable 
that they were formerly continuous with those of the Southbury 
and Connecticut Valley areas of Connecticut. Evidence of such 
an extension for the Palisades trap sheet has been recently pre- 
sented by Julien.^ 



Age of the Faults. 

That the principal period of faulting was subsequent to the 
formation of the intrusive trap masses, as well as the sediments 
and the extrusives is evident from the following considerations : 
(i) The numerous faults by which all these rocks are displaecd 
throughout the area. (PI. XXVIII). (2) The shearing off of 
one side of the Passaic Basin syncline, including the extrusive 
trap sheets and the uppermost strata of the series, by one of the 
great faults of the northwestern boundary, and the arms of the 
intrusive trap of Cushetunk Mountain by another. (3) The 
extrusive trap at Sand Brook is cut and the great intrusives of 
Sourland Mountain, Mount Gilboa, and Byram are brought up 
in a repeated sedimentary series by the Hopewell and Eleming- 
ton faults. .(4) No intrusive trap in the Newark area has yet 
been found to follow or to send off branches along any of these 
fault fissures, and hence there is no evidence of igneous activity 
either during or subsequent to these disturbances. 

April 10, 1907. 



* Science, New Series, vol. 25, 1907, p. 184. 



The Newark (Triassic) Copper Ores 

of New Jersey. 



BY J. VOI.NEY I.EWIS. 



CONTENTS. 

Introduction. 

Acknowledgments. 

Copper-bearing minerals in the trap. 

Copper ores in the sedimentary rocks. 

The Griggstown (Rocky Hill) copper mine. 

Location. 

History. 

Extent of workings. 

Geology. 

Character of the ores. 

Occurrence of the ores. 

Prospects. 
The Arlington (Schuyler) copper mine. 

Location and history. 

Extent of workings. 

Nature and occurrence of ores. 

Prospects. 
The Flemington copper mine. 

Location and histdry. 

Extent of workings. 

Character and occurrence of ores. 

Prospects. 
The Somerville copper mine. 

Location and history. 

Extent of workings. 

Equipment. 

Character of the ore. 

Occurrence of the ore. 

Prospects. 
Old mines at Chimney Rock and Plainfield. 

Mines near Chimney Rock. 

Mines near Plainfield. 

Prospects. 

(131) 



132 THE STATE GEOLOGIST. 

Copper deposits back of First Mountain. 

The Hoffman mine. 

Pluckamin to Feltville. 
The New Brunswick copper mines. 

The New Brunswick or French mine. 

The Raritan mine. 
The Menlo Park copper mine. 

Location and history. 

Geologic conditions. 

Character and occurrence of the ores. 

Prospects. 
Copper ores in other localities. 

Copper ores .at Glen Ridge. 

Copper and silver at Newtown. 

Copper ores at Fort Lee. 

On Pennington Mountain. 
Origin of the Newark (Triassic) copper ores. 
Weed's hypothesis. 

Objections to Weed's hypothesis. 
A hydrothermal hypothesis. 

Origin of ores with intrusive traps. 

Origin of ores without associated intrusives. 

Summary of origin. 
Age of copper ores. 



INTRODUCTION. 

Since early in the eighteenth century the copper deposits of 
New Jersey have attracted more or less attention, and have been 
the objects of rep^eated attempts to mine and smelt them. In 
the early days some of these efforts were quite successful for 
the times ; but for half a century, at least, they have uniformly 
led to disappointment and failure, and since the development of 
the great native copper deposits of Lake Superior and the ex- 
tensive ore deposits of the west and southwest they have almost 
dropped out of mind. From time to time, however, one locality 
or another has been taken up, some of the old workings reopened 
and perhaps a little additional work done, only to be abandoned 
again after a few months or a few years. Such, in brief, has 
been the history of the New Jersey copper industry for nearly 
two centuries. Since the establishment of the State Geological 
Survey the various reports have recorded the rise and fall of 
these i)eriodical waves of interest. 



TRIASSIC COPPER ORES. 133 

The fact is that, with one or two exceptions, little or nothing 
is positively known of the degree of success attained in the early 
operations, except that for one reason or another they were not 
permanently successful. It is known, however, that it was often 
difficult, and even impossible, to drain the workings except to 
very shallow depths; that concentration, beyond hand cobbing, 
was in most cases crude and inefficient; and that, in the later 
times, efforts have often been ill-directed and money wasted for 
useless appliances. 

It may reasonably be questioned whether, in any case, the 
average grade of available ore has been satisfactorily established, 
and it is quite certain that nowhere has the existence of any 
great body of ore yet been demonstrated. This is the more to 
be regretted because in some instances considerable deposits may 
reasonably be expected, and, with proper direction, the money 
already expended upon them would have determined the matter 
long ago. In the following report, however, all available in- 
formation is given concerning every deposit of past or present 
importance, together with such conclusions as may safely be 
drawn from present knowledge, and, in a few cases, suggestions 
as to future operations. 

Whether or not any of these mines shall ever again prove 
commercially profitable, they constitute an exceedingly interest- 
ing example of a class of ore-deposits, and are ot considerable 
importance in investigating the principles of their origin. It is 
hoped that the discussion under this head may contribute some- 
thing toward the advancement of this branch of applied geology. 
This will have been accomplished, in a measure at least, if these 
observations serve to direct the attention of geologists to these 
deposits and to stimulate discussion. 



ACKNOWI.EDGMENTS. 



The author is especially indebted to Mr. W. S. Valiant, assist- 
ant in the Geological Museum of Rutgers College, for careful 
and thorough determination and verification of the minerals en- 
countered in the ores and trap rocks in this study. Thanks are 



134 THE STATE GEOLOGIST. 

also due to the officers and owners of the mines near Rocky Hill, 
Arlington, and Somerville for courtesies extended in the exami- 
nation of the properties, and to Mr. Thomas A. Edison for in- 
formation in regard to the old workings near Menlo Park. Re- 
ports and published articles referred to in the text are duly- 
acknowledged in footnotes. 



COPPER-BEARING MINERAI.S IN THE TRAP. 

Visible grains of chakopyrite (the brassy-yellow copper-iron 
sulphide) are not infrequently found in the trap rocks, particu- 
larly in the intrusives, where the constituent minerals are de- 
veloped in larger grains and hence are more distinct. The same 
mineral also occurs commonly with the abundant calcite and 
zeolites resulting from the alteration of the more vesicular and 
cavernous portions of the extrusive traps, and in veins of similar 
secondary minerals generally. Flakes and thin sheets of metallic 
copper are also found in veins and joint-cracks, and more rarely 
rounded shot-like and irregular granules of copper occur in the 
more massive portions of the trap of First Mountain. Such 
occurrences are frequently encountered in the American Copper 
Company's mine north of Somerville and in the quarries at Chim- 
ney Rock, north of Bound Brook. At the latter locality metallic 
copper is sometimes found in the trap as much as 40 or 50 
feet from the base of the sheet. 

Copper is also known to occur as a constituent of the pyroxenes^ 
the principal dark-colored mineral of the trap rocks. Weed^ cites 
200 assays of the trap of First Mountain, made for Josiah Bond, 
which yielded an average of one-fortieth of one per cent, of 
copper. The fresh central portions of trap prisms were also 
crushed and the heavy minerals concentrated by "horning." 
These, upon examination by Hillebrand, in the laboratory of 
the United States Geological Survey, showed an appreciable 
amount of copper. 

For the purposes of this investigation, typical specimens of 
the coarse-grained intrusive trap from the quarry at Rocky Hill 



*Ann. Rep. of State Geologist for 1902, p. 136. 



TRIASSIC COPPER ORES. 135 

were crushed, and separated by heavy solution in the laboratory 
of the Geological Survey. The pyroxene thus obtained was 
tested for copper by Mr. R. B. Gage, and yielded 0.019 per cent., 
nearly one-fiftieth of one per cent. 

Along oxidized and stained joint-cracks of the various trap 
masses chrysocolla (the bluish-green copper silicate), a little 
malachite (the green carbonate) and, more rarely, azurite (the 
blue carbonate), not infrequently occur. These are manifestly 
the results of alteration of some of the copper-bearing con- 
stituents of the trap described above, by means of the percolating 
surface waters that have partially altered the trap itself. 



COPPER ORES IN THE SEDIMENTARY ROCKS. 

The only ores of copper that have thus far attracted attention 
in the Newark rocks of New Jersey as of possible commercial 
value occur in the shales and sandstones. (See PI. XXX.) They 
consist of disseminated grains and irregular masses, with occa- 
sional vein-like aggr^fates and impregnated fault-breccias. 
Seventy years ago Professor Rogers concluded "that the ore does 
not exist in any instance in the shape of a true vein," but that 
it "has been injected into the body of the red shale and sand- 
stone" of the regular stratified series.^ 

The principal copper-bearing minerals are chalcocite (copper 
glance, the black copper sulphide), and native copper. Asso- 
ciated with these are varying amounts of secondary copper 
minerals that have resulted from alteration by surface waters. 
The chief of these is chrysocolla^ (the bluish-green copper sili- 



* Report of the Geol. Survey of N. J., Henry D. Rogers, Philadelphia, 
1836, pp. 167, 169. 

* Without exception the available literature of the Newark copper deposits 
places the emphasis on malachite as the important secondary ore, whereas 
the present studies of the copper minerals, both in the mines and in the col- 
lections at Rutgers College, -show a great preponderance of chrysocolla in 
every instance. More or less green carbonate is usually present (rarely 
azurite), but the silicate occurs in great abundance. This curious predilec- 
tion for malachite is doubtless the result of unverified tradition accepted 
without question by each succeeding generation, since the error was not 
sufficiently evident to be detected on casual inspection. 



136 THE STATE GEOLOGIST. 

cate), and there are smaller quantities of cuprite (the red copper 
oxide), malachite (the green copper carbonate) and azurite (the 
blue copper carbonate) . 

The modes of occurrence and associations of these ores are 
quite varied, as regards both the sedimentary and the igneous 
rocks. They may be classified, however, under four distinct 
types, two with and two without accompanying intrusive traps, 
as follows: 

I. With intrusive trap rocks. 

1. In the zone of metamorphic, or "baked," sedimentary rocks 
accompanying the intrusive traps, as at the Griggstown (Rocky 
Hill) mine. 

2. In unaltered sandstones and shales intersected by small trap 
dikes, as in the Arlington and Flemington mines. 

II. Without associated intrusives. 

1. In unaltered (or but slightly altered) strata associated 
with extrusive trap sheets, as at numerous localities along First 
Mountain, near Pluckamin, Somerville, Bound Brook and Plain- 
field. 

2. In unaltered strata entirely apart from known trap masses 
of any kind, as at New Brunswick, Glen Ridge and Newtown. 

THE GRIGGSTOWN (rOCKY HII.I.) COPPER MINE. 

Location, — ^This mine, the property of the New Jersey Copper 
Cb-mpany, is located i mile south of Griggstown, 2 miles north- 
east of Rocky Hill, the nearest railway station, and J4 a mile 
east of the Millstone River and the Delaware and Raritan Canal. 
It has also been called the Franklin mine. 

History, — As early as 1753 a newspaper reported that "a valu- 
able Copper Vein of Six Foot Square is very lately found there, "^ 
and various shares in the mine were offered for sale about 12 
years later. It is said that 160 Welsh miners were employed in 
the mine at one time before the Revolutionary War, and that 
considerable ore was concentrated and shipped to England. It 



^ Pennsylvania Gazette, Jan. 16, 1753, reprinted in New Jersey Archives, 
vol XIX, p. 234. 



TRIASSIC COPPER ORES. 



137 



was again operated early in the nineteenth century and several 
later attempts have been made to work the mine by reopening 
portions of the old workings. In 1906 the deepest shaft was 
cleared to the bottom, probably for the first time in over a cen- 
tury. 

Extent of workings, — ^The principal shaft is 190 feet deep 
(Fi?- 5)' "^^^ workings of the first level, about 100 feet deep, 



COPPER MINE 

HIM ROCKY HILL 
SOMfRSET COUNTir, H,J. 







^MUi *t IM> rt UVCL 




Pig' 5. 
Map and section of the old workings at the Rocky Hill Mine (Griggstown) 



also communicate with the surface by an inclined shaft and by 
a drainage tunnel 1080 feet long. There are several other 
shafts now caved in, and some stoped-out chambers of con- 
siderable size, as shown in figure 5. 

Geology, — ^The crest of the ridge rising east of the mine is 
the outcrop of coarse-grained intrusive trap rock, which con- 
tinues southwestward and connects with the larger sill of similar 



138 THE STATE GEOLOGIST. 

rock that forms the crest of Tenmile Hill and Rocky Hill. This 
northeastward offshoot of the trap has been intruded conformably 
between the strata of the shales, which strike N. 45° E. at the 
mine and dip from 10° to 20° N.W. Throughout the length of 
this ridge and westward along Rocky Hill, the shales overlying 
the trap have been greatly altered by the heat of the intrusive 
mass. This is most noticeable in the change of color which they 
have undergone. On the lower slopes of the ridge, below the 
mine, the normal dark-red color appears. Further up the slopes 
this gradually changes, through various shades of purple to the 
dark-gray, brown and almost black homstone that is found in 
the mine. It is often thickly spotted with rounded and rectangu- 
lar masses of chlorite (probably an alteration product of cor- 
dierite), ranging in size from minute specks to an inch in diameter. 

Offshoots of the underlying trap sill form several dikes through 
the shales. One of these about 60 feet thick was cut in the work- 
ings just west of the shaft, and several oval and irregular out- 
crops appear in the vicinity to the west and north of the mine. 
It is clear also that the trap cannot lie far below the present 
workings, if it continues approximately conformable to the strata, 
and any great extension in the depth of the mine would have to 
be made to the northwest. 

Character of the ores, — The essential ore at this mine is 
chalcocite, or glance (the black copper sulphide), with occasion- 
ally a little chalcopyrite (the brassy-yellow copper sulphide), and 
small quantities of secondary chrysocolla (the bluish-green cop- 
per silicate), malachite (the green copper carbonate), and cuprite 
(the red copper oxide). Associated with the ore-minerals are 
frequently found tourmaline, magnetite, hematite, epidote, and 
occasional feldspar crystals, besides the abundant nodules of 
chlorite, described above. 

Native copper, tenorite and bornite have been reported from 
this mine,^ but a careful search of the mine, the old dumps, and 
old collections from this locality in the Geological Mluseum of 
Rutgers College failed to verify any of these. A small quantity 
of native copper is, however, to be expected, and the chalcocite 



' Weed, Bull. U. S. Geol. Survey, No. 225, p. 188. 



TRIASSIC COPPER ORES. 139 

is frequently so intimately mingled with magnetite and hematite, 
as shown by microscopic sections of the ore, as to be readily 
mistaken for bornite with the ordinary blowpipe reactions. Some 
of the soft black masses of magnetite, hematite, or tourmahne 
also present physical characters much like tenorite. 

Occurrence of the ores. — Chalcocite is the original ore. It 
occurs in fissures an^ brecciated zones in the hard, .flinty horn- 
stone, which is sometimes bleached to a light gray or white in 
the vicinity of the ore. The chalcocite also penetrates minute 
cracks in the homstone, and occurs as a constituent of some of 
the chlorite nodules with which the stone is often thickly studded. 
One of the bedding-planes of the hornstone carries fronf 3 to 12 
inches or more of soft, clay-like material charged with ore. This 
material bears evidence of slipping, and seems to have been de- 
veloped along a thrustplane following the stratification. It 
seems to have furnished most of the ore in the earlier workings. 

The secondary ores, chrysocolla, cuprite, and malachite, formed 
from the later alteration of chalcocite and chalcopyrite by per- 
colating surface waters, occur with the primary ores in the fis- 
sures and brecciated zones. They also penetrate the adjoining 
strata along joints and bedding planes to a considerable distance, 
and large masses of the rock are sometimes impregnated with 
, the green stains of chrysocolla. Cuprite and malachite are far 
less abundant. 

Prospects. — So far as accessible the old workings do not show 
any considerable amount of workable ore. All such bodies as 
were encountered seem to have been pretty thoroughly stoped 
out. The conditions under which the ores were found seem to 
be of greater extent than the old workings, however, both laterally 
and in depth, so far as may be judged from those at present 
known. Since the mine has been reopened probably to the greatest 
depth attained here, it is worth while to determine whether or 
not this is true, and if so to extend the drifts beyond the limits 
of the old workings in prospecting for further bodies of work- 
able ore. 



140 THE STATE GEOLOGIST. 

THE ARLINGTON (SCHUYLEr) COPPER MINE. 

Location and history. — This mine is located in North Arling- 
ton, Hudson County, about a mile northeast of Arlington station 



Fig. 6. 
Map of Arlington, showing trap rocks, fault and old copper \ 
(Schuyler Mine), after Darton. 



Pig- 7- 
Cross section at A, figure 6, Arlington (after Darton). 

on the N. Y. & Greenwood Lake Railroad, and about 8 miles 
from New York City. (Fig. 6.) It is the oldest mine in the 
State and was probably the first cc^per mine operated in America. 



TRIASSIC COPPER ORES. 141 

It was discovered early in the eighteenth century, probably about 
1 7 19, and a shipment of no casks of ore from New York in 
1 72 1 was probably the first exported from this mine. In spite 
of serious trouble with water in the lower levels, the mine was 
extensively worked in Colonial times and was a source of con- 
siderable wealth, for the times, to its owners, the Schuyler family. 
Since the Revolution the mine has been repeatedly reopened and 
operated for longer or shorter periods, and at one time (1859- 
1865) it is said that 200 laborers were employed in the mine and 
mills. An expensive mill and reduction plant designed to treat 
125 tons a day were erected at the mine in 1900, but short ex- 
perimental runs proved that it was not adapted to the ore, and 
the mine has now lain idle for several years. 

Extent of workings. — "The Victoria shaft is reported to be 
347 feet deep, but all is mud below the 240-foot level and diffi- 
cult of access. (Fig. 8.) The old Cornish pump is still in posi- 
tion in the bottom of the shaft, buried in mud and fallen timbers. 
It is said that there are three drifts from the bottom of the shaft, 
one toward the northwest about 180 feet long, one running south- 
west 180 feet long, and the third running north about 210 feet. 
The mill at this time was near the mine and had 25 stamps of 
the old Cornish type with wooden stems. The ore as it came 
from the mine was cobbed and handpicked. The high-grade 
material was shipped without further treatment, and the lower 
grade was concentrated by jigs and buddies." ^ In all 42 shafts 
are said to have been sunk on the property, but only one, the Vic- 
toria, has been kept open. There are also 3 drain tunnels, one of 
which drains the mine to the lOO-foot level. Two inclines have 
been run in from the face of the bluff overlooking the Newark 
Meadows. One of these is 220 feet long and the other 80 feet.^ 
Figure 8 shows the workings above the 240-foot level. 

Nature and occurrence of ores, — The ore at Arlington is chaU 
cocite, or copper glance (the black copper sulphide) with much 



^ J. H. Cranberry, Engineering & Mining Jour., vol. LXXXII, 1906, p. 11 18. 

'Annual Report of State Geologist for 1902, p. 129. The number of shafts 
Jhas also been given as 32, and other details of the old workings vary some- 
what in the different descriptions. See Engineering & Mining Journal, Vol. 
69, 1900, p. 135, and Vol. 82, 1906, p. 11 16. 

10 GEOL 



142 



THE STATE GEOLOGIST. 



secondary chrysocolla (the bluish-green copper silicate), and 
smaller amounts of malachite (the green copper carbonate). A 
little azurite (the blue copper carbonate), cuprite (the red copper 
oxide), and occasional particles of native copper are also found. 
The ore occurs in unaltered gray arkosic sandstone, which is 





Fig. 8. 

Map and section of the old workings at the Schuyler Copper Mine. 

Engineering and Mining Journal, vol. 69, p. 135.) 



(After 



penetrated by small irregular branching trap dikes and over- 
lain by red shale. The chalcocite is found chiefly in branching 
veins and seams in the sandstone near the small dikes and in the 
frequent fault breccias of sandstone and trap. (Compare fig. 7.) 
The larger pockets of the ore sometimes exhibit cleavage faces 



TRIASSIC COPPER ORES. 143 

an inch in width. These masses are sometimes thickly filled with 
quartz grains or with minute reddish crystals of feldspar. The 
sandstone is irregularly stained with the green chrysocoUa and 
also contains occasional scattering grains of chalcocite. This im- 
pregnated sandstone occurs in two layers, the upper about 12 feet 
thick and the lower about 10 feet, separated by one foot of shale, 
these have a westerly dip of about 9 degrees. The workings have 
been chiefly confined to the upper sandstone. 

"Over wide areas in this mine the surface of this sheet [of in- 
trusive trap] is smooth and conformable to the gently dipping 
sandstones, but there are irregularities in which the strata are 
crossed for a few feet, and the sheet also sends several offshoots 
up into the sandstone. It is stated that the diabase surface was 
followed westward for a half a mile in the mining operations, 
and that at one point it is traversed by a fault of considerable 
amount." ^ 

Prospects. — Systematic sampling by a competent mining en- 
gineer in 1900 is said to have given an average of slightly more 
than 2 per cent, of copper for the upper sandstone, as exposed in 
the present workings, and a little less than that amount for the 
lower sandstone. A small amount of silver is always present, but 
probably not enough to repay cost of recovery. ^ If an average of 
2 per cent, copper content can be established over any large part of 
the property, the question of successful mining would seem to re- 
solve itself into the questions of economic reduction and compe- 
tent management. The sandstone can be mined and crushed very 
cheaply on a large scale, and rich seams and pockets of glance in 
the fault breccias and along the courses of the thin trap dikes 
might be expected to add appreciably to the output of the mine 
in the future, as they have done in the past. At any rate the mine 
is worthy of conservative investigation, in spite of past failures, 
by extending the drifts so as to block out systematically a large 



' N. H. Darton, U. S. Geol. Survey, Folio No. 83, p. 10. 

* It is of interest in this connection to note that a blowpipe assay of a rich 
specimen of ore from this mine, made in the Mineralogical Laboratory of 
Rutgers College by Mr. Harry R. Lee, yielded 4.4 oz. of silver per ton and a 
gold bead that was distinctly visible. 



144 THE STATE GEOLOGIST. 

body of ore, or by thorough exploration with a core-drill. If a 
large body of workable ore can be thus established, the most 
economical method of treatment should be very carefully deter- 
mined and the plant so modified as to adapt it to the character of 
the ore. 

THE FI.EMINGTON COPPER MINE. 

Location and history, — The mine is located half a mile south- 
west of the court house in the town of Flemington, Hunterdon 
County. The ore was evidently discovered prior to 1834, since 
it is referred to in a publication of that date as having been 
"lately discovered, but not yet extensively explored.''^ It has 
been said that work was also done here "in the early days," but 
there seems to be no record of this. Active operations were under 
way, however, at the time of Professor Rogers visit in. 1835,^ 
and it is said that $400,000 were expended in opening and equip- 
ping the mine. Afterwards various attempts to operate it were 
made by several companies, and much prospecting was done in 
the effort to establish min/&s in the region from Flemington to 
Copper (Hill, 2 miles to the south. All of these undertakings 
were soon abandoned, however, and no active operations have 
been attempted since 1860.^ 

Extent of workings. — The workings were located immediately 
beside a brook, and pumping must have been necessary from the 
beginning. A mill and a smelter were erected, of perhaps 25 
tons capacity, judging from the dilapidated portions of the plant 
still standing, and considerable active work was done, as attested 
by the large dump-heaps about the old shafts. Several shafts 
were opened, but their depth and the extent of other underground 
workings have not been learned. 

Character and occurrence of ores. — The ore was found in partly 
altered brownish-red and purplish shales in the vicinity of trap 
dikes. It consisted essentially of chalcocite (the black copper sul- 



*A Gazetteer of the State of New Jersey, by Thos. F. Gordon, Trenton, 

1834. 

* Rept. Geol. Sur. of N. J., by Henry D. Rogers, Philadelphia, 1836, p. 167. 

* History of Hunterdon and Somerset Counties, New Jersey, by Jas. P. 
Snell, Philadelphia, i88i. 



TRIASSIC COPPER ORES. 145 

phide), cuprite (the red copper oxide), chrysocolla (the bluish- 
green copper silicate), and malachite (the green copper car- 
bonate), associated with calcite. Chcdcopyrite (the brass-yellow 
iron-copper sulphide) is often disseminated in grains through the 
larger masses of chalcocite. A series of trap dikes cuts the shales 
and sandstones northward from the great intrusive sill of Sour- 
land Mountain to Flemington. It is in the sediments accompany- 
ing these dikes that the copper ores of the region from Copper 
Hill to Flemington occur. 

Professor Rogers^ described the conditions in a series of east 
and west cuttings that were^being made across the ore-body at 
the time of his visit. "A belt of metalliferous rock" was un- 
covered "of very variable width, sometimes as wide as 20 or 30 
feet, which preserves nearly a north and south direction for 
several hundred feet," with strong indications of a precisely 
similar ore 2 miles to the south. The ore is described as "in- 
timately blended or incorporated with the semi-indurated and 
altered sandstone, and the mass has therefore somewhat the aspect 
in certain portions of a conglomerate of recemented fragments, 
the metalliferous part being the cement. Most commonly the 
ore is thus minutely disseminated, though now and then it occurs 
in lumps of great purity and considerable size." 

Prospects, — ^The geological conditions are seen to be closely 
similar in many respects to those of the Schuyler mine at Arling- 
ton, but much less is known of the value and extent of the ore 
bodies encountered. In the absence of such information, nothing 
can be said that might in any way offset the discouraging experi- 
ence of those who have attempted at various times to operate the 
mine. 

THE SOMERVIIvLE COPPER MINE. 

Location and history, — ^This is the old Bridgewater mine, 
located 3 miles north of Somerville, Somerset County, on the 



* Rept. Geol. Sur. of N. J., by H. D. Rogers, Philadelphia, 1836, p. 169. 



146 THE STATE GEOLOGIST. 

southwestern slopes of First Mountain. The ore was known 
here and some of the old drifts in the vicinity were run before 
the Revolutionary war. Active work was again begun in 1821 
and continued more or less intermittently at many points from 
this mine southeastward to Chimney Rock, a distance of 4 
miles, during the next two decades. In the meantime a smelter 
was erected at Chimney Rock and another near the Bridgewater 
mine. Some mining was also done east of Chimney Rock in 
1866. No further work was done until 1881, when explorations 
were again begun at the Somerville mine, and drifts were run 
into the mountain side along the 'contact of the trap and the 
underlying shales. Similar exploratory work has been done at 
intervals since, especially in the extension of the work along the 
under contact of the trap. 

Extent of workings. — The principal opening is a sloping 
tunnel, or incline, following the contact of the shales with the 
overlying trap, as explained above. This contact plane dips 
slightly more than 10 degrees toward the northeast, and the 
tunnel has been driven into the mountain 1,240 feet. Drifts of 
varying length have been opened on alternate sides of the incline 
at intervals of 30 feet, and in a few instances considerable 
chambers have been excavated. The aggregate length of incline 
is 1,400 feet, and of side drifts 2,040 feet. A drainage tunnel 
catches the surface waters that find their way into the mine and 
also drains the upper workings. The water ifrom the lower 
portions is also pumped into this tunnel 

The old dumps along the mountain slopes toward the southeast 
show that many tunnels of considerable length have been run 
between the mine and Chimney Rock. On the east side of the 
gorge at Chimney Rock, also, a tunnel 300 ifeet long runs into 
the mountain to the contact of the trap and branches each way 
along this contact for 100 feet, while another tunnel was driven 
only 20 feet below it.^ 

Equipment, — ^The mining plant consists of an 80-horse power 
boiler, a 5-drill Rand compressor, running drills and pumps, and 
a hoist with a 12-horse power Lidgerwood engine. The 50-ton 



* Cook, Geology of New Jersey, 1868, p. 677. 






TRIASSIC COPPER ORES. 147 

mill is equipped with 60-horse power boiler and engine, crusher, 
two sets of roughing rolls, drying screens, sizer, and two Wilfley 
tables.^ 

Character of the ore. — ^The ore of the Somerville mine is essen- 
tially native copper, altered above the depth of 100 feet (600 feet 
on the slope) to cuprite (red copper oxide), chrysocolla (green 
copper silicate), and malachite (the green copper carbonate). 
Small grains and crystals of chalcocite (black copper sulphide) 
and occasional particles of chalcopyrite (the brass-yellow iron- 
copper sulphide) also occur, besides small amounts of hydro- 
cuprite (orange-colored hydrous copper oxide). The copper 
is silver-bearing and now and then small masses of native silver 
are found. 

Occurrence of tlie ore, — The ore occurs chiefly in the upper 
two and a half feet of shales (varying from i to 3 feet) 
immediately underlying the extrusive trap sheet, and penetrating 
the trap itself usually to a distance of about 6 inches from the 
contact with the shales. Locally the copper is found to extend to 
much greater distances in both the shales and the trap. In 
driving the drainage tunnel in the underlying shales, metallic 
copper was found in nodules 8 feet below the trap, and a sheet 
of cuprite coated with malachite was encountered 15 feet below 
the contact.^ In the trap quarries at Chimney Rock, on the 
other hand, numerous nodules flakes and sheets of copper have 
been found in the trap as much as 40 or 50 feet above the base of 
the sheet. 

In the shales the copper occurs in minute grains and strings 
and in nodules, sheets, and ragged masses of great variety of 
form and size. Many years ago a mass plowed up in a field 
on the mountain slope near the mine is said to have weighed 
128 pounds. A portion of it now in the Geological Museum 
of Rutgers College weighs 74 pounds, including perhaps a pound 
of attached and included shale. The shale containing the copper 
is bleached to various shades of reddish brown, gray and almost 
white. Immediately about even the smallest grains, and to a 



* Ann. Rep. State Geologist for 1902, p. 129. 

•Ann Report of State Geologist of N. J. for 1903, p. 109. 



148 THE STATE GEOLOGIST. 

varying distance (a fraction of an inch to one or two inches) 
from them, the inclosing shale is invariably of much lighter color 
than the prevailing brownish red of other portions of the same 
stratum and of adjacent regions. These bleached spots and mot- 
tlings, while fairly well defined, are not separated by a sharp 
boundary from the surrounding red shale. There is generally a 
distinct transition zone of intermediate shades from an eighth 
to a quarter of an inch or more in width. Also the thin lamina- 
tion, which is distinct in normal portions of the rock, often dis- 
appears altogether in the bleached spots about the copper. 

The red shales of this and adjoining regions to the south, east 
and west are frequently interspersed with thin tabular crystals 
and clusters of calcite, which range in size from almost invisible 
to more than an inch in diameter. (PL XXXI, A.) They are 
apparently low flat rhombohedra. Often near the surface and 
usually in the mine this calcite has been partly or wholly re- 
moved by solution. In adjacent regions the cavities are often 
lined with microscopic quartz crystals, and sometimes divided 
by thin partitions of quartz, presumably deposited along cleav- 
age planes of the calcite. In the mine, where the cavities are all 
quite small, slit-like openings, they are often partly occupied by 
little masses of copper and crystals of chalcocite; and this is 
equally true of both the bleached and unbleached portions of the 
shale. (PI. XXXI, B.) It would seem, therefore, that these 
belong to a different period of formation from that of the prin- 
cipal mass of the ore, which was deposited only in the bleached 
areas of the shale. Occasional crystals of prehnite and chal- 
copyrite also occur in these minute cavities near the trap. 

In the upper 600 feet of the slope most of the copper has 
been oxidized to cuprite, chrysocolla and malachite, which re- 
place the disseminated particles, sheets and masses of the metal. 
The base of the trap sheet is often vesicular and the cavities have 
been filled with quartz, manganocalcite and zeolites, with fre- 
quent lumps and stringers of copper. A northeast-southwest 
fault encountered in the workings has displaced the strata about 4 
feet, and has crushed and sheared the rocks considerably in places. 

Prospects, — ^The mine requires no timbering, the overlying 
sheet of solid trap forming a perfect roof. ' The ore is easily 



Geological Survey, 1906. 



Fig. A. Red shale with desseminated lenticular calcite. New Brunswick. 



pij ^rrr] ^Tg '' F pw^''i^J "^T"Uiil | •]jpri'|^jr"P7"l'ff"" TJPiifl' ';!31T|''TJ',iTi'|i|i|'HJit!I| 



TRIASSIC COPPER ORES, 149 

mined and crushed, the inclosing rock being softer than the some- 
what similar ores of the Lake Superior region. There is no 
reason to doubt that the character of the ore will continue native 
copper in depth, as in the last 600 feet of the slope, which has 
evidently passed below the zone of oxidation. Repeated sam- 
plings in recent years are said to have yielded an average copper 
content of over 2 per cent, in the present workings. If a great 
body of ore of this grade can be fully established there seems to 
be no good reason why it should not be mined .at a profit, if 
operated on a large scale. With the great advantages of its 
location as to labor and fuel supply and its accessibility to the 
markets of the East, its possibilities as a low-grade copper mine 
•are worthy of investigation, and explorations should be suffi- 
ciently extended to determine definitely the question of available 
ore-supply for a considerable working period. Incidentally the 
character as well as the quality and quantity of the ore would 
thus be tested, and the type of mill required for its economical 
treatment could be fully determined experimentally. No exten- 
sive plant should be erected until this is done. 



OLD MINES AT CHIMNEY ROCK AND PI^AINFlElvD. 

Mine^ near Chimney Rock, — Similar conditions to those de- 
scribed, which prevail along First Mountain for 4 miles south- 
eastward, led to considerable work in the early days as far as 
Chimney Rock and beyond. On both sides of the gorge of Middle 
Brook at Chimney Rock numerous old workings are found, and 
many of the drifts were several hundred feet in extent. One 
on the east side of the brook is said to Have been driven in 300 
feet to the trap and 100 feet each way along the contact. On 
the. west side one of the old tunnels is said to have penetrated 
700 feet. One of the old smelters, built early in the last century, 
was also located here. A drift now open beneath the trap quarry 
at Chimney Rock shows conditions almost identical with those 
described above, although the shales are somewhat less bleached 
about the disseminated ores than at the Somerville mine. Occa- 
sional pieces of native silver are also found associated with the 



ISO THE STATE GEOLOGIST. 

copper at this locality. As noted above, grains and strings of 
copper are now found here in the trap quarries as much as 40 or 
50 feet above the base of the sheet. 

Mines near Plainfield, — Northwest of Plainfield, in the gorge 
of Stony Brook through First Mbuntain, extensive explorations 
were made for copper early in the last century, and active mining 
was going on- there at the time of Dr. Cook's visit in 1866, the 
ores being sent to Bergen Point. Work was being done by two 
companies at that time, and tunnels and drifts of several hundred 
feet had been opened on both sides of the gorge, the longest 
tunnel in each case being given as 400 feet. 

The workings being in the oxidized zone the ores were the 
same as in the upper workings at the Somerville mine, impreg- 
nating the shale for a thickness of from 8 inches to 2 J^ feet from 
the trap. The shales here dip 10 to 20 degrees a little west of 
north. No ore was found in the base of the trap itself. Small 
faults of 3 or 4 feet throw were encountered in places.^ 

Prospects. — Practically nothing definite is known of the grade 
or extent of ore encountered in these old workings. As small un- 
dertakings, under the adverse conditions of earlier times, they 
were not successful, presumably for the reason that the amount of 
rich ore encountered was very small. If, however, future explora- 
tions should establish the existence of large bodies of workable 
low-grade ore at one point along the base of First Mountain, 
there would be every reason for the careful investigation of other 
points where similar deposits are known to exist. 



COPPER DEPOSITS BACK OF EIRST MOUNTAIN. 

The Hoffman mine. — Two miles northwest of the Somerville 
mine and three- fourths of a mile southeast of Pluckamin is the 
old Hoffman mine, which has been worked at various times and 
was said to have produced some ore for shipment. The shaft, 
136 feet deep, penetrates the shales and sandstones and the under- 
lying trap. The ore is said to be 4 feet thick and to carry 



* Cook, Geology of New Jersey, 1868, pp. (176, 677. 



TRIASSIC COPPER ORES. 151 

some native copper. Materials collected from the old dump 

• 

show chalcocite in sandstone and in brecciated trap, with smaller 
quantities of green carbonate (malachite). The breccia seems to 
indicate that the ore occurs in connection with a zone of faulting. 

Pluckamifii to Feltville. — From this point around the inner or 
back slope of First Mountain for a distance of 17 miles, copper 
minerals have been found at several places between the vesicular 
upper portions of the trap and the overlying sandstones and 
shales. Discovery of these minerals has led to prospecting in 
the vicinity of Martinsville, Warfenville, Washingtonville, and 
Feltville. The work at all these places was done many years ago, 
however, and the conditions encountered are not known. At 
Feltville the ore was said to be sulphide, probably the black sul- 
phide, or glance, as at the Hoffman mine. It was associated 
with pyrite in a thin rock-seam between the trap and the shales. 
The contact as now exposed along the narrow ravine and in 
some of the old pits and drifts shows no copper minerals. 

THE NEW BRUNSWICK COPPER MINES. 

The Nem Brtmswick or French mine. — ^About 1748 to 1750 

* 

many lumps of native copper weighing from 5 to 30 pounds 
each, "upwards of 200 pounds" in all, were plowed up in the 
field of Philip French, now Neilson Campus of Rutgers College, 
at New Bnmswick. A company was formed to mine for copper 
in 1750 and work was begtin by sinking a shaft the following 
year. Grains of the metal were found in the red shales and sheets 
in the joint-planes of the rock. Some of the latter of the "thick- 
ness of two pennies and three feet square" are said to have been 
found within 4 feet of the surface. 

A depth of 60 feet or more was attained and some of the work- 
ings are said to have extended several hundred feet under the 
Raritan River, although there was much difficulty in handling the 
water. A stamp-mill was erected and many tons are said to have 
been shipped to England.^ Similar sheets of metallic 'copper 



* Morse's Gazetteer; Morse's "American Universal History," 1805; Barber 
and Howe's "Historical Collections of the State of N. J., New York, 1844." 



152 * THE STATE GEOLOGIST. 

from one-sixteenth to one-eighth of an inch in thickness and 
one or two feet across have been found in grading the street 
east of the campus of Rutgers College, and also in digging a 
cellar on Somerset street on the southwest side of the campus. 
The latter place has been recently partly exposed again, and the 
copper is found in a zone of bleached grayish shale and in spots 
of gray mottled with the normal red color along an east-west 
fissure. The conditions. are an exact duplicate of those found 
at Menlo' Park, described below, except in the direction of the 
fissure, which is at right angles. Cuprite (the red oxide) and 
malachite (the green carbonate), with occasionally a little chry- 
scfcolla (the silicate) and azurite (the blue carbonate), are some- 
times found incrusting such metallic sheets or entirely replacing 
them in the joint cracks of the shales. There is no evidence or 
indication that trap rock was ever encountered in these old work- 
ings at New Brunswick. The well back of the Rutgers College 
gymnasium, 244 feet deep, and one at Johnson & Johnson's fac- 
tory, 480 feet deep, are both in the immediate vicinity of the old 
copper mine, while th*e one on Bishop Place, 455 feet deep, is 
little more than a block to the north of it. In all of these the 
usual red shales of the region were penetrated, with occasional 
purplish and sandy layers. The purple shales, which are also 
occasionally seen at the surface in this vicinity, may indicate the 
presence of intrusive trap at no great depth. 

The Raritan mine. — About 3 miles southwest of New 
Brunswick is the old Raritan mine. "The main shaft was 160 
feet deep, from which a timnel was driven in a north-northeast 
direction. Another shaft northeast of this one did not reach the 
ore. All of them are now filled with water. The rock of these 
shafts lying at the mouth of the mine is mostly red and bluish 
shales. Very little trap was seen in these rubbish heaps. The 
ore is mostly a carbonate with some sulphide. The difficulty in 
working this mine was the trouble with water."^ The workings 
were not far from some small dikes that are known to intrude 
the shales in that vicinity, and may possibly have encountered 
some di these. Otherwise the conditions are apparently the same 
as at New Brunswick. 



* Cook, Geology of New Jersey, 1868, p. 679. 



TRIASSIC COPPER ORES. 153 



THE MENLO PARK COPPER MINE. 

Location and history, — The old workings are half a mile north 
of Menlo Park and 7 miles northeast of New Brunswick. Copper 
was discovered here, it is said, about 1784,^ and the workings 
were so old in 1820 that "no vestiges of copper remain upon the 
surface/'^ Attempts were made to work the mine before the war 
of 181 2, again in 1827, and in the eighties of the last century. 
Later spasmodic efforts have been made from time to time, and a 
stock company, organized early in the present century, installed 
hoisting and pumping machinery, a tube mill, and jigs, and carried 
on explorations during the greater part of the year 1903. 
Nothing is known of the equipment used in the earlier work. 
So far as known, no ore was ever shipped, and the workings never 
proceeded beyond the stage of exploration. The deepest shaft 
is said to be 120 feet deep, with drifts and galleries of unknown 
extent. 

Geologic conditions. — ^The shales of the vicinity have the usual 
bright-red to brownish-red color and dip 12 degrees toward the 
north. At the mine they are traversed by a vertical north-south 
fissure (PI. XXXII), along which the movement has been parallel 
to the bedding, a nearly horizontal shove, or heave. This is in- 
dicated by both the slickensided walls and breccia of the fault 
and the abrupt termination of the fissure beneath undisturbed con- 
formable shales above. The fault-breccia, varying from 6 inches 
to 2 feet in thickness, and about 3 feet of each wall of the 
fissure are composed of the dark-gray, nearly black, soft shale 
referred to as carrying the ore. On each side of the fissure this 
color quickly changes, after a little mottling of gray and red, into 
the normal red color of the typical Brunswick shales. In the 
different layers there is considerable irregularity in the distance 
at which this change takes place, but the average is perhaps 3 
feet from the walls of the fissure. The zone of blackened 



^W. W. Clayton, History of Union and Middlesex Counties, New Jersey, 
Philadelphia, 1882, p. 849. 
'American Journal of Science, ist sen, vol. 2, 1820, p. 198. 



154 THE STATE GEOLOGIST. 

material traceable from the top of the fissure in a nearly horizontal 
position to the westward probably indicates that the heave here 
follows a bedding-plane. Owing to the indistinctness of the 
exposure, however, it is impossible to determine this point 
definitely. Locally the dark-gray shale is spotted and mottled 
to a slight extent by white bleached areas. No trap debris is 
visible about any of the workings, and probably none occurs here. 

Character and occurrence of the ores, — The ore is native cop- 
per, altered in part to civrysocolla (green copper silicate), in dark- 
gray shale constituting the breccia and walls of a fault fissure. 
There are also minute grains of chalcapyrite (brass-yellow 
copper-iron sulphide) and of magnetite in the dark-colored shale. 

The copper occurs as thin sheets and films in joint cracks of 
the dark-gray shale and plating the slickensided surfaces of the 
breccia and walls. In the form of minute grains and strings it 
also permeates the mass of the shale and occasional bituminous 
plant remains. ChrysocoUa is chiefly confined to the joints and 
fissures, while chalcopyrite occurs very sparingly in minute dis- 
seminated particles through the body of the shale. 

Prospects.-^Mr, Thomas A. Edison, who did some work here 
about twenty-five years ago, writes in answer to an inquiry : "The 
ores were too lean to pay. Of the streak we worked, which was 
about four feet wide, the average was about one-half per cent." 
It is said that the last operations produced ore that averaged over 
2 per cent., but authentic information to this effect is lacking. 
At any rate there seems little probability that there is a great body 
of ore at this place, such as a deposit of low grade would require 
for profitable exploitation, and there is, therefore, no encourage- 
ment for further expenditures in exploration. 



COPPER ORES IN OTHER LOCAUTlES. 

Copper ores at Glen Ridge, — Traces of old workings are still 
to be seen at Glen Ridge, 4 miles northwest of Newark, in the 
area just east of the public school building. CkdlcQcite (black 
copper sulphide) and chrysocolla (the bluish-green silicate) are 
found penetrating and largely replacing bituminous plant remains 



Geological Survey, iqo6. PLATE XXXII. 



Heave fault. Old copper n 



fe* v 



(•»r '. 



•«*?■. 

"-»» 



!*» 



t'. 



TRIASSIC COPPER ORES. 155 

in black glossy masses looking much like anthracite coal. Gray 
sandstone is also stained green by impregnations of chrysocoUa, 
as in the Arlington mine. No trap is known to occur here or in 
the surrounding region for several miles, and local outcrops are 
not sufficient to determine whether or not there are fault fissures 
in the strata. Copper minerals in exactly the same association 
are found in certain strata of the old sandstone quarries at Avon- 
dale, north of Newark and Belleville, and also in a quarry a mile 
and a half northeast of the Schuyler mine. 

Copper and silver at Newtown, — Native silver in small scales 
and specks occurs in gray sandstone stained with chrysocoUa on 
George Drake's farm at Newtown, 4 miles north of New Bruns- 
witk. Only surface specimens have been collected, and there has 
been no prospecting for ores. As at Glen Ridge, described above, 
no trap rocks occur here nor within a distance of several miles in 
the adjacent regions. 

Copper ores at Port Lee, — Small amounts of chalcopyrite (cop- 
per pyrites), with some "malachite^' (probably chrysocolla, the 
silicate) were discovered in the sandstones under the trap of the 
Palisades at Fort Lee in very early times, and some exploratory 
work was done in the hope of developing a gold mine. 

On Pennington Mountain. — On the southern and southwestern 
slopes of Pennington Mountain, i to 2 miles northwest! of 
Pennington, traces of copper minerals have been found in the 
altered shales adjacent to the intrusive trap mass which forms the 
backbone of the mountain. These have led to occasional pros- 
pecting operations on a small scale, but no notable amount of 
ore has been located, nor is any to be expected. 

Enough copper is often present to produce green chrysocoUa 
stains in the shales and sandstones near the trap masses, both ex- 
trusive and intrusive, but experience teaches that it is not wise 
to base sanguine expectations of ore deposits on such "indi- 
cations." Nothing illustrates better than such copper stains the 
accuracy of the old precept that "one swallow doesn't make a 
summer." At the various localities just described. Glen Ridge, 
Newtown, Fort Lee, and Pennington Mountain, known condi- 
tions give no reason to expect more than such scant discolor- 
ations. 



156 THE STATE GEOLOGIST. 

ORIGIN OF THE NEWARK (TRIASSIC) COPPER ORES. 

Whatever the economic aspects of these Triassic copper ores 
they must continue to possess considerable scientific interest as 
problems in ore-deposition. The comparatively simple structural 
relationships of the ores and associated rocks relieves them of 
the difficulties and uncertainties attendant upon the complicated 
structures that prevail in many important mining districts. The 
conclusions arrived at, when satisfactorily established, should 
therefore be correspondingly simpler and clearer and should find 
profitable application in regions where the problems are more 
involved. It is largely with a view to the scientific value of the 
deposits that these studies have been undertaken, and it is hoped 
that the attention of geologists may be drawn to both the im- 
portance and accessibility of these examples for the elucidation 
of questions of ore genesis. 

Kemp^ has suggested that the copper of these deposits has 
probably come from the chalcopyrite disseminated through the 
trap or from copper in the pyroxene of these rocks, but makes 
no reference to mode of accumulation. 

Weed's hypotliesis. — In 1902, Weed^ suggested the possibil- 
ity of some close connection between igneous activities and the 
origin of the ores associated with intrusive trap rocks. He says : 
"At Rocky Hill glance and hematite occur under conditions that 
suggest a hydrothermal origin, and at Arlington also the con- 
ditions indicate a reimpregnation of the overlying rocks, with 
subsequent slight alterations and migrations of the copper.'' 

Later, however, after an examination of the Rocky Hill mine, 
he ascribes the ores to the influence of percolating surface waters 
in the partial alteration of the trap. He says '? 

*'The scientific interest of this deposit is very great on account 
of the evident reducing action of the hornblende and chlorite 
upon copper-bearing solutions, but the discussion of the origin 



* Ore Deposits of the United States, 2d ed., p. 168 ; 5th ed., p. 223. 
'Ann. Report State Geologist N. J. for 1902, p. 131. 

• Bulletin U. S. Geological Survey No. 225, 1904, p. 189. 



TRIASSIC COPPER ORES. 157 

of the ore involves a consideration of the various cycles of up- 
lift and erosion to which the region has been subjected since 
Triassic time, and the accompanying movements of percolating 
\vaters, which are supposed to have derived the copper from the 
alteration of the trap from a fresh basaltic lava or diabase sheet 
to its present somewhat altered condition." 

This is the conclusion he had formerly arrived at in regard 
to the ores beneath the trap sheet of First Mountain, an extru- 
sive mass.^ For the latter he gives the following probable se- 
quence of events: (a) Basalt chloritized, iron reduced from 
silicate to ferrous oxide; (&) calcite amygdules formed in basalt 
and pores of the altered shale bed; (c) copper dissolved out by 
percolating waters and carried downward; (d) copper and cal- 
cite deposited in pores of the ore; (e) glance reduced and ferric 
oxide reduced in white patches. For this last step he finds that 
"the readiest agent at hand to reduce the glance to native copper 
is humic acid in waters containing oxygen," and "where organic 
matter such as plant remains occurred, the copper sulphide would 
be reduced to native copper." He further supposes that the solu- 
tions carrying the copper "contained alkaline carbonates, and 
precipitated copper and glance with calcite." 

Objections to Weed's hypothesis, — ^Many of the difficulties in- 
volved in the foregoing hypothesis were fully appreciated by the 
author himself, who, after summing up the conditions of occur- 
rence, states that "it is hard tO' see how any single chemical se- 
quence can account for facts apparently so contradictory, and it 
may be like Vogt's Norwegian cases, an example of reversed con- 
ditions." He also demonstrates how impossible it is to adapt 
the commonly accepted explanation of the Lake Superior ores to 
the New Jersey deposits. He says : 

"From the complete absence of iron oxide with the copper ore, 
and from the fact that the native copper occurs only in those 
portions of the ore-bed in which the ferric oxide has been re- 
duced, a phenomenon common to Bolivian and European de- 
posits as well as these, it is evident that the commonly accepted 
explanation is not only not adequate, but contrary to the observed 



^ Annual Report of the State Geologist of N. J. for 1892, pp. 136-139. 
II GEOL 



158 THE STATE GEOLOGIST. 

facts. If it were the protoxide of iron or of magnetite ferrous 
solutions that caused the reductions we should have red spots 
and ferric oxide, one of the most insoluble and stable of sub- 
stances, associated with the native copper." 

Some further difficulties in the application of Weed's hypo- 
thesis may be enumerated as follows : 

( 1 ) The trap rock of First Mountain is not sufficiently altered 
to account for the ores underlying it. On the basis of one-fortieth 
of one per cent, of copper in the unaltered trap, one-fourth of 
this would have to be transferred without loss from a trap sheet 
600 feet thick, in order to supply two feet of the underlying 
shales with an average of 2j4 per cent, of copper. The great 
bulk of the trap is believed to be much less altered than this 
supposition would demand. 

(2) An intricate system of meteoric circulation would be re- 
quired to account for the ores overlying the trap sheet on the 
back of First Mountain and for the deposits above the intrusive 
trap rocks at the Arlington and Rocky Hill mines. If these ores 
have been derived from the alteration of the underlying trap 
masses, as supposed by Weed, to supply those lying above the 
First Mountain trap an upward movement of the copper-bearing 
solutions is required, whereas exactly the reverse supposition has 
been made in order to bring down the copper for the ores beneath 
the trap. 

(3) The ore at Arlington not only lies chiefly above the in- 
trusive trap, but its amount is out of all proportion to the thin 
sheets of this rock that have thus far been found in the vicinity 
of the mine. No tests have been made to determine the copper 
content of the unaltered portions of these traps, but unless this 
should prove to be far in excess of examples thus far determined 
in the New Jersey traps, the ore bodies here would not only 
require all the copper from the accompanying dikes and sheets, 
but in addition a much larger supply would be needed from some 
unknown source. 

(4) Weed supposes that the solutions carrying the copper 
"contained alkaline carbonates, and precipitated copper and 
glance with calcite" in a porous stratum of shale. An examina- 
tion of the shales of the adjacent regions to the south and south- 



TRIASSIC COPPER ORES. 159 

west shows that the normal red Brunswick shales are often thickly 
interspersed with thin tabular crystals and clusters of crystals of 
calcite, which range in size from almost invisible to more than 
an inch in diameter. This calcite, therefore, is a normal con- 
stituent of the shales and has not been supplied from the trap, 
and the peculiar slit-like pores in the shale of the upper oxidized 
ores in the Somerville mine, are the result of leaching out of 
these tabular calcites. 

(5) Calcite occurring in amygdaloids and in fissures of the 
trap and the shales has undoubtedly been derived, like the zeolites, 
from the alteration of the trap rocks by percolating waters, and 
is in no way to be associated m origin with the calcite in the 
body of the shales. Such calcite with accompanying zeolites 
doubtless began to form with the beginning of erosion and per- 
colating waters inaugurated by the deformation of the Newark 
strata, and continues to the present time. 

(6) While the humic acid supposed to reduce the copper to 
a native metallic state is presumably furnished by percolating 
waters from the surface, it is also supposed that "where organic 
matter, such as plant remains, occurred the copper sulphide would 
be reduced to native copper." When present, orgianic matter 
undoubte^ily produces these results, as shown by specimens ob- 
tained at M'enlo Park and Glen Ridge, but the prevailing bar- 
renness of the red Brunswick shales in this respect is well known. 
Were it otherwise the well nigh universal ferric coloring would 
present a chemical problem no less difficult than that of the cop- 
per ores themselves. Practically no organic matter occurs in 
the Somerville mine, replaced or otherwise, and the quantities 
found in connection with other copper ores of the State are wholly 
inadequate to account for more than a minute fraction of the 
total deposit. 

(7) Weed's hypothesis fails to account in any manner for 
those ore-deposits that are in no way associated with trap rocks, 
as at New Brunswick, Menlo Park, Glen Ridge and Newtown. 
At all of these localities the underlying Palisades intrusive must 
be some thousands of feet below, and the extrusive sheet of 
First Mountain, if extended, would lie at a still greater distance 
above. The only known nearer trap masses in any of these 



i6o THE STATE GEOLOGIST. 

cases are thin dikes and equally thin sheets sometimes connected 
with them, and even these are seldom near. 

A HYDROTHERMAIw HYPOTHESIS. 

The copper ores lie in a broad curved belt (See map, PL 
XXX) above the great intrusive sill of the Palisades and Rocky- 
Hill and, with few small exceptions, below the extrusive trap 
sheet of First Mountain. As explained in the preceding pages, 
these deposits may be grouped into two general classes ; namely, 
those with intrusive trap rocks and those without such associa- 
tions. Of the latter, some are under or over the lowest extru- 
sive sheet of the Watchungs, and others are out in the midst 
of the broad shale areas entirely apart from trap rocks of any 
kind. It is also clear, from the foregoing descriptions of the 
various deposits, that the ores of each of the leading types are 
remarkably uniform in character, the essential ore associated with 
intrusives being chalcocite, or glance, while apart from such asso- 
ciation native copper chiefly occurs. 

Origin of ores zvith intrusive traps, — The close association of 
these ores \vith intrusive sills, dikes and apophyses, and their 
position chiefly above such intrusives in the Griggstown (Rocky 
Hill) and Arlington mines leave little doubt that there is a genetic 
connection. That this is not merely a derivation through later 
alteration of the trap rocks by percolating waters and the simul- 
taneous removal of the contained copper in solution is demon- 

« 

strated by two conditions referred to above, namely, the posi- 
tion of the ores chiefly above instead of below the trap masses, 
and the quantity of ore as compared with the small amount of 
known trap rocks, especially at the Arlington mine. 

Th'ere remains, therefore, the hypothesis of heated copper- 
bearing solutions, and. possibly vapors, arising from the greater 
underlying mass of intrusives along the dikes and accompanying 
fissures, and depositing chalcocite in the immediate vicinity while 
still highly heated. Under the great pressure of overlying forma- 
tions and the cooling influence of the surrounding strata, vapors 
probably could not exist more than a very short distance from 
the greater intrusive masses ; and the chief effects may, therefore, 



TRIASSIC COPPER ORES. i6i 

be safely ascribed to solutions, probably magmatic waters emanat- 
ing directly from the molten lava. 

At the Griggstown mine and vicinity the Rocky Hill intrusive 
sill, which lies but a few hundred feet below, sent up irregular 
dikes and finger-like apophyses into the overlying shales. Some 
of these now appear as the little round.ed outcrops of trap that 
are scattered over this region. The shales are fissured but little, 
and this was undoubtedly confined, in the main, to the immediate 
vicinity of the intrusive. Shales more than a mile in thickness 
overlie this region, and many parts of these are highly charged 
with crystals of calcite. It is quite possible that some reaction of 
the solutions with this mineral have contributed to the deposition 
of the copper-bearing mineral, chalcocite. 

At the Arlington mine the impregnated sandstone is penetrated 
by dikes and by thin sheets along the bedding planes. The solu- 
tions rose along the fissures of intrusion and their branchings in 
the adjacent sediments and penetrated the breccias and porous 
sandstones, impregnating them with ore. Doubtless waters also 
rose to higher horizons and escaped freely to the surface or 
formed ore deposits that have been subsequently removed by 
erosion. Similar conditions also exist at Flemjngton, where the 
ore-bearing solutions followed the intrusive dikes and accom- 
panying fissures. 

Origin of ores! zinthout associated intnisives, — It has been 
demonstrated^ experimentally in the laboratory of the U. S. 
Geological Survey that a solution saturated with cuprous sul- 
phate will deposit metallic copper on cooling, and that, therefore, 
a solution in which cupric sulphate has been partly reduced to 
cuprous sulphate by ferrous sulphate, pyrite, chalcocite, siderite, 
or silicates rich in ferrous iron, will deposit metallic copper if 
carried to a cooler region. It was also shown that if silver 
sulphate is present with the cuprous sulphate the silver will be 
deposited, on cooling, before the copper, and, hence, the two 
metals will appear in separate masses instead of combining to 
form an alloy. 



^H. N. Stokes, Economic Geology, vol. i, 1906, pp. 644-650. 



i62 THE STATE GEOLOGIST. 

In conformity with these results the Newark copper ores of 
the second type (that is, apart from intrusive trap) .are readily 
conceived to be deposits from waters heated by and probably 
emanating from the great underlying intrusive trap sheet and its 
various branchings and ramifications through the sediments. 
Such waters must have permeated the strata over a wide area at 
the time of the intrusion of the traps and during the long period 
of slow cooling that followed, especially along the fissures and 
joint-cracks of the overlying shales, sandstones, and extrusive 
trap sheets. These waters were probably acid solutions of cu- 
prous sulphate derived directly from the trap, and carrying a little 
silver and a trace of gold in solution. Their movements through 
the sediments were sufficiently obstructed in certain localities to 
permit a considerable accumulation of deposits through progres- 
sive cooling. 

Probably these deposits were also augmented at times by 
chemical reactions between the solution and certain constituents 
of the inclosing rocks. As already described, the typical shales 
of this region are often more or less calcareous and contain 
minute crystals and small clusters of tabular calcite disseminated 
through them. Observations in many well-known mining regions 
have demonstrated the efficacy of this mineral as a precipitating 
agent in the formation of ore-deposits wherever the solutions are 
sufficiently retarded in their movements to permit the reactions to 
occur. At the same time the calcite would be thus removed in 
part, leaving the characteristic hollow, slit-like spaces more or 
less occupied by copper or copper-bearing minerals. In the same 
manner the ferric oxide coloring matter of the red shales has 
been leached out by the acid waters, leaving the grayish and 
whitish spots that mark the impregnated portions of the rock. 

Such waters as escaped upward through the more extensive 
dislocations were intercepted in the vicinity of Somerville, Bound 
Brook and Plainfield by the extrusive trap sheet of First Moun- 
tain, and thus the layer of shale immediately beneath became 
charged with metallic copper. Some portions of the solution, 
however, found passage through the joints and fissures in the 
trap; and thus metallic copper is found in the midst of the trap 



TRIASSIC COPPER ORES. 163 

in the quarries at Chimney Rock, and small amounts of ore occur 
on top of the trap sheet of First Mountain and beneath the over- 
lying shales of Washington Valley, at intervals from Pluckemin 
to Feltville. 

At New Brunswick the underlying Palisades-Rocky Hill intru- 
sive trap sill is probably as near as at the Arlington mine, and 
dikes that penetrate the shales to within a short distance of the 
city to the east, south and southwest, give evidence of widespread 
Assuring. Heavy ledges of sandstone underlie the shales at this 
place, as seen in the old quarries at the boat landing. The native 
copper and various secondary minerals derived from it, however, 
are in joints and fissures of the impervious overlying shales. 
Similar conditions seem to have prevailed at Newtown, where 
native silver is found associated with copper ores. The ores 
found at Glen Ridge are also doubtless of exactly the same char- 
acter. The deposits in this case may have been fed by an exten- 
sion of the same system of fissures through which the Arlington 
ores were brought up. 

At Menlo Park the ores are confined to the breccia and walls 
of a well-marked heave-fault, through which the ore-bearing 
solutions must have come; and the abrupt termination of the 
fissure above makes it reasonably certain that they could only 
have come upward. At this and several other localities occasional 
bits of bituminous vegetable remains are found more or less 
infused with copper-bearing minerals, but not more so than much 
of the adjacent rock that is entirely barren of such materials; 
and in no case could the organic matter, even if all replaced, 
account for more than a very small amount of the ore actually 
deposited. 

Summary of origin, — In all cases the Newark (Triassic) cop- 
per ores of New Jersey are attributable to the same source, 
namely, hot copper-bearing solutions, doubtless magtnatic waters, 
deriving both their heat and their copper salts from the great 
underlying Palisades-Rocky Hill trap sill and its offshoots. The 
deposition of chalcocite in the heated portions near the intrusives 
and of native copper with a little chalcocite in the more remote, 
and, therefore, cold regions may, in both cases, have been chiefly 



i64 THE STATE GEOLOGIST. 

the result of cooling, supplemented perhaps in part by reactions 
with the widespread calcite of the sedimentary rocks. The con- 
ditions of extensive accumulation have been supplied by some 
relatively impervious member, a dense shale or a trap sheet, 
which has sufficiently impeded the movements of the uprising 
solutions to permit considerable cooling, and, therefore, extensive 
deposits, and also to allow time for possible reactions with the 
calcite of the sediments, and for leaching out the ferric coloring, 
in part, by the acid waters. 

AGE O^ THE COPPER ORES. 

From the foregoing descriptions of the various ore deposits of 
this region it is clear that in many localities they are closely asso^ 
ciated with the great Palisades-Rocky Hill instrusive trap sill, as 
at Griggstown, southwest of New Brunswick, and at Arlington. 
It is equally evident that the deposits along First Mountain, as 
at Somerville, Bound Brook and Plainfield, are of later origin 
than the overlying trap sheet, for they penetrate the trap itself, 
and small deposits of ore are found above the trap sheet and be- 
neath the overlying shales. 

The time of deposition of the ores is therefore correlated with 
the intrusion of the Palisades sill, which is regarded as their 
source, and subsequent to the extrusive flows of the Watchung 
Mountains. Other reasons for placing the date of the intrusive 
trap after the extirusives are discussed on pages 125-127. The 
ores were formed, therefore, very near the close of the Newark de- 
position in this region, and the great igneous intrusion may well 
have marked the beginning of those disturbances that led to the 
tilting and faulting of the whole series. 

April 10, 1907. 



Properties of Trap Rocks for Road Construction* 



BY J. VOI.NEY LEWIS. 



Crushed trap rock for road construction was produced to the 
value of more than half a million dollars a year by the quarries of 
the State during the years 1903 and 1904, in addition to large 
amounts for railroad ballast and for concrete. The merits of 
this stone for the building of macadam roads have become gen- 
erally known throughout the country, but it is not all equally 
adapted for all roads, as abundantly demonstrated by both ex- 
perience and laboratory tests of the stone from the various 
quarries. Hence it was deemed advisable, in connection with the 
study of the geology and petrography of the trap rocks, to collect ^ 
specimens from the more accessible localities and submit these to 
the Office of Public Roads, Department of Agriculture, Washing- 
ton, D. C, for systematic examination of their properties for 
road construction. 

The accompanying table and diagram represent the results of 
these tests, including some half a dozen samples that had been 
previously submitted by others. In the column designated 
"French coefficient of wear," the higher the number the more 
durable the rock; higher values also indicate superior '^Hardness" 
and "Toughness" in the next two columns. Under "Cementing 
value" the higher numbers show greater binding power of the 
finely powdered material. In further explanation of these proper- 
ties as affecting the adaptability of a stone for road building, the 
following is quoted from Mr. L. W. Page, Director of the Office 
of Public Roads '} 



* Yearbook of the U. S. Department of Agriculture for 1900, p. 351. 

(i6s) 



i66 THE STATE GEOLOGIST. 

"By hardness is meant the power possessed by a rock to resist the wearing 
action caused by the abrasion of wheels and horses* feet. Toughness, as 
understood by road builders, is the adhesion between the crystals and fine 
particles of a rock, which gives it power to resist fracture when subjected to 
the blows of traffic. This important property, while distinct from hardness, 
is yet intimately associated with it, and can, in a measure, make up for a 
deficiency in hardness. Hardness, for instance, would be the resistance 
offered by a rock to the grinding of an emery wheel ; toughness the resistance 
to fracture when struck with a hammer. 

"Cementing or binding power is the property possessed by the dust of a 
rock to act after wetting as a cement to the coarser fragments composing 
the road, binding them together and forming a smooth, impervious shell over 
the surface. Such a shell, formed by a rock of high cementing value, protects 
the underlying material from wear and acts as a cushion to the blows from 
horses' feet, and at the same time resists the waste of material caused by 
wind and rain, and preserves the foundation by shedding the surface water. 
Binding power is thus probably the most important property to be sought for 
in a road-building rock, as its presence is always necessary for the best 
results. 

"The hardness and toughness of the binder surface more than of the rock 
itself represents the hardness and toughness of the road, for if the weight 
of traffic is sufficient to destroy the bond of cementation of the surface, the 
stones below are soon loosened and forced out of place. When there is an 
absence of binding material, which often occurs when the rock is too hard 
for the traffic to which it is subjected, the road soon loosens or ravels. 

"Experience shows that a rock possessing all three of the properties men- 
tioned in a high degree does not under all conditions make a good road 
material; on the contrary, under certain conditions, it may be altogether 
unsuitable. As an illustration of this, if a country road or a city parkway, 
where only a light traffic prevails, were built of a very hard and tough rock 
with a high cementing value, neither the best, nor, if a softer rock were 
available, would the cheapest results be obtained. Such a rock would so 
effectively resist the wear of a light traffic that the amount of fine dust worn 
off would be carried away by wind and rain faster than it would be supplied 
by wear. Consequently, the binder supplied by wear would be insufficient, and 
if not supplied from some other source the road would soon go to pieces. 
The first cost of such a rock would in most instances be greater than that of 
a softer one, and the necessary repairs resulting from its use would also be 
very expensive. * * * 

"The degree to which a rock absorbs water may also be important, for in 
cold climates this to some extent determines the liability of a rock to fracture 
by freezing. It is not so important, however, as the 'absorptive power of the 
road itself, for if the road holds much water the destruction wrought by 
frost is very great. This trouble is generally due to faulty construction 
rather than to material. The density or weight of a rock is also considered 
of importance, as the heavier the rock the better it stays in place and the 
better it resists the action of wind and rain." 



TRAP ROCK FOR ROADS. 167 

THE SELECTION OF A STONE I^OR MACADAM ROADS. 

As stated above, a stone of the greatest hardness, toughness, 
and cementing power does not make the best road under all cir- 
cumstances ; in fact such material would give the best results only 
under the most severe conditions of heavy traffic. It is equally 
true that a stone of the same general kind or class does not 
always possess these properties in the same degree. The trap 
rocks, for instance, vary greatly in their texture, chemical com- 
position, and degree of alteration, and these variations affect 
to a marked degree the properties of the stone for road con- 
struction. 

The trap rock produced by the various quarries varies from 
exceedingly dense, fine-grained and even partly glassy condition 
to a coarse-grained, granitic texture, in which the individual 
minerals are developed in grains of one-fourth of an inch or 
more in diameter. Under the microscope the "habit" of the 
mineral particles is seen also to vary greatly ; in some cases they 
are of about equal" dimensions in every direction, tending toward 
a rounded form, in others they are greatly elongated, lath-shaped 
and rod-shaped forms. Other things being equal, fine-grained 
varieties and those composed of interlocking, elongated minerals 
possess a higher degree of toughness. 

Variations in chemical composition are accompanied chiefly 
by corresponding variations in the proportions of the minerals 
pyroxene and feldspar (labradorite), the two principal constitu- 
ents of the trap rocks of this region. Of these the former pos- 
sesses the greater toughness and the latter the greater hardness. 
In some of the more basic varieties olivine (chrysolite) may con- 
stitute as much as 10 per cent, of the rock. This mineral is 
somewhat harder even than the feldspar, but it is usually more 
or less altered into serpentine, which is considerably softer. The 
pyroxene is also subject to extensive alteration into greenish 
chloritic minerals, which are also much softer than the original 
mineral. The feldspar is somewhat less subject to extensive 
alteration, but is often partly changed into a soft white powdery 
kaolin. 



i68 THE STATE GEOLOGIST. 

Thus it will be readily understood that while some trap rocks 
are very hard and tough and suited only for heavy-traffic roads, 
there are others that are not suited to such severe conditions and 
are better adapted to suburban streets, park ways, and country 
roads. Too often, however, the selection of the material for 
road building is made solely with a view to convenience or cheap- 
ness of the stone, with the result that an inferior road is con- 
structed and the economy in first cost is more than counter- 
balanced by the expense of maintenance. Such initial careless- 
ness mav result in the selection of a stone that is too hard and 
tough for the traffic to which it is subjected or one that is too 
soft and brittle. 

"If the surface of a macadam road continues to be too muddy or dusty 
after the necessary drainage precautions have been followed, then the rock 
of which it is constructed lacks sufficient hardness or toughness to meet the 
traffic to which it is subjected. If, on the contrary, the fine binding material 
of the surface is carried off by wind and rain and is not replaced by wear of 
the coarser fragments, the surface stones will soon loosen and allow water 
to make its way freely to the foundation and bring about the destruction of 
the road. Such conditions are brought about by an excess of hardness or 
toughness of the rock for the traffic. Under all conditions a rock of high 
cementing value is desirable; for, other things being equal, such a rock 
better resists the wear of traffic and the action of wind and rain." 

The different classes o-f traffic have been divided into- five 
groups, according to volume and character, as follows : 

1. City traffic, such as exists on the business streets of large 
cities. The conditions are too severe for any macadam, and more 
resistant forms of pavement must be used. 

2. Urban traffic, that of the less severe city conditions, but 
subjected to heavy traffic and requiring the hardest and toughest 
macadam. 

3. Suburban traffic, that of suburbs of larger cities and main 
streets of country towns, requiring a macadcim of high tough- 
ness but somewhat less hardness than the preceding. 

4. Highway traffic, such as exists on the principal country 
roads. A rock of»medium hardness and toughness is best. 

5. Country-road traffic, that of the less frequented country 
roads. For this it is best to use a comparatively soft rock of 
medium toughness. 



TRAP ROCK FOR ROADS. 



169 



In the diagram, figure 9, the Scimples are arranged according 
to the French coefficient of wear, beginning with the greatest 




Pig. p. 

Diagram showing tests on trap rock as road metal. 

and decreasing toward the right, while hardness, toughness, and 
other properties vary irregularly. Therefore those stones that 



lyo THE STATE GEOLOGIST. 

fall on the left-hand side and toward the middle of the diagram 
and show at the same time great hardness and toughness are best 
adapted to urban and other very heavy-traffic uses; while those 
in the middle of the diagram with moderate hardness and tough- 
ness, and toward the left with lower or toward the right with 
higher values of these properties, are suitable for suburban and 
heavy-traffic highway purposes. Those toward the right-hand 
side with medium and further to the left with low hardness and 
toughness are adapted to lighter suburban and ordinary high- 
way traffic conditions. Even the softest and most brittle material 
in the list is too resistant for the best results on the less fre- 
quented country roads, unless combined with softer materials 
to furnish the necessary fine powder for cementing. 

It should be a matter of interest to all who are in any way 
responsible for road construction or maintenance, as well as to 
owners of quarries supplying road materials, to know that the 
U. S. Department of Agriculture has a fully equipped road- 
material laboratory, where any person residing in the United 
States may have tests made free of charge by applying for in- 
structions to the Office of Public Roads, Dept. Agriculture, Wash- 
ington, D. C. Acknowledgements are due to Mr. L. W. Page, 
director of this office, for the valuable data presented in the 
accompanying table and for many courtesies extended during 
the collection and testing of the materials. 

April ID, 1907. 



TRAP ROCK FOR ROADS. 



171 



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THE STATE GEOLOGIST. 



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PART IV. 



Notes on the Mining Industry* 



By HENRY B. KUMMEL. 



(173) 



12 GEOL, 



Notes on the Mining Industry* 



BY HENRY B. KUMMEl^. 



THE IRON MINES. 

During 1906 the following iron rhines were producers: the 
Washington and Ahles, at Oxford ; the Hurd, Richard and Hoff, 
at Wharton; the Mount Hope mines, at Mount Hope; the 
Hude, at Stanhope; the Andover, DeCamp, Upper Wood and 
Wharton, at Hibemia; the Dickerson, at Ferro Mont; and the 
Peters, at Ringwood. Development has been carried forward 
at the Teabo and Scrub Oak or Dell, but these are not yet to be 
classed as producers. 

The total product during the year was 542,488 long tons, a 
gain over the figfures of 1905. The steady increase since 1897 in 
production as shown by the figures on page 180 are certainly 
encouraging. The value of the ore at the mines is estimated at 
$1,560,000. 

At the Ahles mine, Oxford, of the Basic Iron Ore Company, 
mining has been carried on from No. i and No. 3 shafts and 
Slope No. 4 has been sunk so that it is expected to reach ore 
early in 1907. As has been mentioned in previous reports, the 
ore from this mine is a mixture of magnetite and limonite, carry- 
ing about 4 per cent, of manganese. With the completion of the 
new slope, it will be possible to increase very largely the annual 
output. The ore is mined by the caving system. 

The Empire Steel and Iron Company, of Catasauqua, Pa., are 
operating only the Washington mine at Oxford, and have done 
considerable development work in that vicinity, and from present 
indications the output of this mine will be largely increased and 
its grade of ore raised when contemplated improvements are 

(175) 



176 THE STATE GEOLOGIST. 

completed. At Mount Hope a new shaft, the Leonard, has been 
opened to mine ore from the Side Hill vein and the Findley vein, 
and it is planned to sink a new shaft on the Brannin vein. The 
Elizabeth mine has been a producer during the year. 

The Musconetcong Iron Company, at Stanhope, has continued 
to operate the Hude mine at Stanhope, and also the Dickerson 
mine at Ferro Mont, but both mines were only small producers. 

The Richard mine, owned by the Thomas Iron Company of 
Easton, has continued to be a large producer and has maintained 
the high record of tonnage of the last few years. 

At the Hoff mine, at Wharton, which was reopened in 1905 
by the Hoff Mining and Realty Improvement Co. of Rockaway, 
N. J., the raising of ore has continued and a new tunnel has been 
started on another vein about half a piile from the old mine. 

All the Joseph Wharton properties have been the scene of 
activity and development. The improvements at the Hurd mine 
at Wharton, commenced in 1905, were carried forward with the 
result that that mine is now a larger producer than for many 
years previous. At the Hibernia mines a new ore body has been 
located a few hundred feet northwest of the one heretofore 
worked. At a depth of 75 feet on the dip, lean ore containing 
about 30 to 32 per cent, of iron was crosscut for a distance of 
35 feet. Further exploratory work upon this body will be made 
this year. The Scrub Oak or Dell mine, northwest of Mine Hill, 
has been pumped out and explored and a new shaft is being 
sunk to a large body of low-grade ore. At the Teabo mine a 
crosscut at the 800-foot level of the new shaft struck a 2-foot 
vein of rich magnetite at a distance of 27 feet in the hanging 
wall, and a thicker ore body on the footwall side at a distance 
of about 40 feet from the shaft. The shaft was then sunk 40 
feet and crosscutting was again commenced to these ore bodies. 

THE ZINC MINES. 

The New Jersey Zinc Company's mines at Franklin have 
shown a large increase in production over that of 1905. During 
the first part of the year most of the ore obtained came from the 
drives extended along the various levels, as in former years. In 



NOTES ON THE MINING INDUSTRY. 



177 



the latter part of the year, however, considerable ore was broken 
from the open cut at the extreme south end of the ore body. 
Cableways, with the necessary bins, were erected, and these are 
expected to handle the ore which lies south of "The Dike." 

A new shaft has been started, which, going down at an angle of 
47J^° in the footwall rock, will command the full depth of the 
deposit and deliver the ore directly into the mill. Very con- 
siderable extensions and additions to the plant are contemplated. 

The company reports a total of 361,330 tons of ore mined 
during 1906. 

THE UMESTONE INDUSTRY. 

In the Annual Report for 1905, the chemical composition of the 
white limestone of Sussex and Warren counties was discussed 
at some length, and a map published showing the distribution of 
the most important areas. The demand for this rock has so in- 
creased that the Survey proposes hereafter to compile annually 
statistics and a brief summary of the industry. 

Qimrries, — ^During 1906, the following firms were quarrying 
the crystalline limestone : 







No 


■ of 








OMce. 


Quarries. Location, 


Chief Use. 


Bethlehem Steel Co. 


South Bethlehem 




McAfee 


Flux 


Bigelow & Swain 


Newark 






Ogdensburg, 


Portland cement 


* 




- 






and flux 


Crestmore Stone Co. 


Dover 






Pinkneyville, 


Portland cement 


Edison Portland 










and flux 


Cement Co. 


Stewartsville 




I* 


(( 


Portland cement 


N. H. Hunt 


Newton 






(( 


Flux and cement 


New Jersey Lime Co. 


McAfee 




3 


Hamburg and 










McAfee 


Lime 


B. Nicoll & Co. 


New York 




3 


Franklin 
Furnace 


Flux 


The Windsor Lime Co. 


Newark 




I 


Hamburg 


Lime 



Prodtict, — The total production during the year, as compiled 
from reports furnished the State Geologist by the producers, was 
459,927 tons. These figures are only approximately correct. 



* In November the Crestmore Stone Company's quarry was leased by the 
Portland Cement Company. 



178 THE STATE GEOLOGIST. 

inasmuch as the returns frohi at least three sources were g^ven 
in round numbers to the nearest thousand, and in one or two 
other instances only to the nearest hundred tons. However, the 
figures cannot be far from; the truth, and can be accepted as 
substantially correct, the probable error being less than one-half 
of one per cent. 

Uses. — It is not possible to determine from the returns the 
rjespective amounts used for various purposes. Apparently by 
far the largest part is used as a flux, both in blast furnaces and 
open-hearth steel furnaces. The demand for Portland Cement is 
also large, and less than 15 per cent, is burned for lime. 

Nem qtutrries. — ^The quarry of Bigelow & Swain was opened in 
July, so that the output there was for but a part of the year. 
According to 16 analyses furnished the Survey by this firm, 
the rock of their quarry, omitting one special sample, has the 
following constitution : 

Maximum. Minimum. 

Silica, 0.82 0.32 

Iron Oxide and Alumina, 0.90 0.20 

Carbonate of Lime, 97-31 94.23 

Carbonate of Magnesia, 4-57 i-43 

One hundred and three carloads of rock shipped the Thomas 
Iron Company were reported to average only 0.55 per cent silica. 
These facts confirm the conclusions published in the Annual 
Report for 1905, that much of the white limestone is a very pure 
non-dolomitic limestone, and also indicate that the fresh rock 
obtainable in a quarry may be purer than indicated by analyses 
of samples taken from surface ledges.^ 

March 15, 1907. 

* Compare Analysis No. 21, p. 184, Annual Report of the State Geologist, 
1905. 



Mineral Statistics^ 

For the Year J906. 
IRON ORE. 

The total production of the mines, as reported by the several 
mining companies, was 542,488 tons. 

The table of statistics is reprinted, with the total amount for 
1903 added. 

TABLE OF STATISTICS. 

Year. Iron Ore. Authority. 

1790 10,000 tons Morse's estimate. 

1830 20,000 tons Gordon's Gazetteer. 

1855 100,000 tons Dr. Kitcheirs estimate. 

i860 164,900 tons U. S. census. 

1864 226,000 tons Annual Report State Geologist. 

1867 275,067 tons " " " 

1870 362,636 tons U. S. census. 

1871 450,000 tons Annual Report State Geologist. 

1872 600,000 tons 

1873 665,000 tons 

1874 525,000 tons 

1875 390,000 tons 

1876 285,000 tons 

1877 315,000 tons* 

1878 409,674 tons* 

1879 488,028 tons 

1880 745,000 tons 

1881 737,052 tons 

1882 932,762 tons 

1883 521,416 tons 

1884 393,710 tons 

1885 330,000 tons 

1886 500,501 tons 

1887 547,889 tons 

1888 447,738 tons 



(( (( (( 

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* From statistics collected later. 



(179) 



i8o THE STATE GEOLOGIST. 

Year. Iron Ore. Authority. 

1889 482,109 tons Annual Report State Geologist. 

1890 .552,996 tons 

1891 551,358 tons 

1892 465455 tons 

1893 356,150 tons 

1894 277,483 tons 

1895 282,433 tons 

1896 264,999 tons 

1897 257,235 tons 

1898 275,378 tons 

1899 300*757 tons 

1900 342,390 tons* 

1901 401,151 tons 

1902 443,728 tons 



(( (( K 

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1903 484,796 tons* " ^ " " 

1904 499,952 tons 

1905 500,541 tons 

1906 542,488 ton^ 



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ZINC ORE. 

The production of the New Jersey Zinc Company's mines is 
reported by the company to be 361,330 gross tons of zinc and 
franklinite ore. It was chiefly separated at the company's mills. 
This report shows a gain in production over 1905 of 38,268 tons. 

The statistics for a period of years are reprinted from the 
last annual report. 

ZINC ORE. 

Year. Zinc Ore, Authority. 

1868 25,000 tonsf Annual Report State Geologist. 

1871 22,000 tonsf 

1873 17,500 tons 

1874 13,500 tons 

1878 14,467 tons 

1879 21,937 tons 

1880 28,311 tons 

1881 49,178 tons 

1882 40,138 tons 

1883 56,085 tons 



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it it it 

ii it it 



* The figures, 407,596 tons, given in the report for 1900, included 75,206 tons 
of crude material which should have been reduced to its equivalent in con- 
centrates. The figures for 1903, given in the report for that year, were incor- 
rect. 

t Estimated for 1868 and 1871. Statistics for 1873-1890, inclusive, are for 
shipments by railway companies. The later reports are from zinc-mining 
companies. 



MINERAL STATISTICS. i8i 

Year, Zinc Ore, Authority. 

1884 40,094 tons Annual Report State Geologist. 

1885 38,526 tons 

1886 43,877 tons 

1887 50,220 tons 

1888 46,377 tons 

1889 56,154 tons 

1890 49,618 tons 

1891 76,032 tons 

1892 77,298 tons 

1893 55,852 tons 

1894 59,382 tons 

1895* 

1896 78,080 tons 

1897 76,973 tons 

1898 99419 tons 

1899 154,447 tons 

1900 194,881 tons 

1901 191,221 tons 

1902 209,386 tons 

1903 279419 tons 

1904 250,025 tons 

1905 323,062 tons 

1906 361,330 tons 



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* No statistics were published in the Annual Report for 1895. 



Publications^ 



It is the wish of the Board of Managers to complete, so far 
as possible, incomplete sets of the publications of the Survey, 
chiefly files of the Annual Reports ' in public libraries, and 
librarians are urged to correspond with the State Geologist con- 
cerning this matter. 

The Annual Reports of the State Geologist are printed by 
order of the Legislature as a part of the legislative documents. 
They are distributed by the State Geologist to libraries and public 
institutions, and, so far as possible, to any who may be interested 
in the subjects of which they treat. 

Six volumes of the Final Report series have been issued. 
Volimie I, published in 1888, has been very scarce for several 
years, but all the valuable tables were reprinted in an appendix 
of Volume IV, of which a few copies still remain, although the 
supply of this volimie is so far reduced that indiscriminate re- 
quests cannot be granted. 

The appended list makes brief mention of all the publications 
of the present Survey since its inception in 1864, with a statement 
of the editions now out of print. The reports of the Survey are 
distributed without further expense than that of transportation. 
Single reports can usually be sent more cheaply by mail than 
otherwise, and requests should be accompanied by the proper 
postage as indicated in the list. Otherwise they are sent express 
collect. When the stock on hand of any report is redttced to 200 
copies, the retnaining volumes are withdrawn from free distri- 
bution and are sold at cost price. 

The maps are distributed only by sale, at a price, 25 cents per 
sheet, to cover cost of paper, printing and transportation. In 
order to secure prompt attention, requests for both reports and 
mtips should be addressed simply "State Geologist," Trenton, 
N.J. 

(183) 



i84 THE STATE GEOLOGIST. 



CATAU)GUE OF PUBUCATIONS. 

Geoi^ogy of New Jersey. Newark, 1868, 8vo., xxiv + 899 pp. Out of print. 
PoRTFouo OF Maps accompanying the same, as follows : 

1. Azoic and paleozoic formations, including the iron-ore and limestone dis- 
tricts ; colored. Scale, 2 miles to an inch. 

2. Triassic formation, including the red sandstone and trap-rocks of Central 
New Jersey; colored. Scale, 2 miles to an inch. 

3. Cretaceous formation, including the greensand-marl beds ; colored. Scale, 
2 miles to an inch. 

4. Tertiary and recent formations of Southern New Jersey ; colored. Scale, 
2 miles to an inch. 

5. Map of a group of iron mines in Morris county; printed in two colors. 
Scale, 3 inches to i mile. 

6. Map of the Ringwood iron mines ; printed in two colors. Scale, 8 inches 
to I mile. 

7. Map of Oxford Furnace iron-ore veins; colored. Scale, 8 inches to i 
mile. 

8. Map of the zinc mines, Sussex county ; colored. Scale, 8 inches to i mile. 

A few copies can be distributed at $2.00 per set. 

Report on the Clay Deposits of Woodbridge, South Amboy and other 
places in New Jersey, together with their uses for firebrick, pottery, etc. 
Trenton, 1878, 8vo., viii + 381 pp., with map. Out of print. 

A Preuminary Catalogue of the Flora of New Jersey, compiled by N. L. 
Britton, Ph.D. New Brunswick, 1881, 8vo., xi -f 233 pp. Out of print. 

Final Report of the State Geologist. Vol. I. Topography. Magnetism. 
Climate. Trenton, 1888, 8vo., xi -f 439 pp. Out of print. 

FtNAL Report of the State Geologist. Vol. II. Part I. Mineralogy. 
Botany. Trenton, 1889, 8vo., x + 642 pp. Unbound copies, postage 22 cents. 
Bound copies, $1.50. 

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Report of Professor George H. Cook upon the Geological Survey of New 
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INDEX. 



A. 

Page 

Ahles mine, 175 

Andover mine (see Hibernia). 

Argillite, tests on, 30, 76 

Arlington copper mine, 140, 141, 143 

trap dikes at, z 19, 12a 

Artesian wells, report on 13 

Assistants on Survey, 3 

Avondale, copper near, 155 

test of stone from, 64 

Azurite 135, 136, 152 

B. 

Baldpate Mountain, 120 

Bartle, W. E., test of stone from, 60 

Bayley, W. S 12 

Bayliss, Geo., test of stone from 66 

Bellville Stone and Quarry Co., test of 

stone from, 64 

Bench-marks, changes of 9 

Berryi E. W 16 

Bethlehem Steel Co., white limestone 

of, 177 

Bigelow & Swain, white limestone of, 178 

Board of Managers, changes in, 3 

Bogota trap dike, 119, 122 

Bound Brook Crushed Stone Co., trap 

tests, 172 

origin of ore at 162 

Bridgewater copper mine 145 

Buckley, tests on stone by 20 

Building stone, report on, xo, 17 

results of tests, 23 

samples tested, 22 

Byram, 117 

C. 

Caldwell, well near, no 

Calcite, precipitation of ore by 162 

Carteret, wells at 118 

Cementing power of road metal, 166 

quality of trap, 171 

Chalcocite, 135, 138, 141, I44, I47, I5i» I54 

Chalcopyrite,...i34, 138, 14s, i47. iS4i iSS 

Chimney Rock, copper mines near,. 146, 149 

ore at, 147 

ChrysocoUa, 135, 

138, 142, 14s, 147, 152, 154, 155 



Page 
Clay in glass sand, 83 

Ooster, test of stone from, 68 

Collections geological, 6 

Commonwealth Quarry Co., trap rock 

tests, 172 

Cooper, E. E., trap rock tests, 172 

Copper-bearing minerals, 134 

Copper minerals in shale, 135 

Copper, native, 135, 142, 147, 151, 154 

Copper ores, age of, 164 

mode of occurrence 136 

origin of, 97, 156, 163 

report on, 131 

summary of origin 163 

thickness of 143, 

I4S» 147, ISO, 152, IS4 

Copper, per cent, in shale 149 

report on, 10 

Correlation of intrusive trap sheets,... 120 

trap sheets, zi6 

Correspondence, 7 

Cranberry Lake, tests of stone from,.. 34 
Crestmore Stone Company, white lime- 
stone of, 177 

Cuprite 136, 138, 142, 145, 147, 152 

Cuprous sulphate, copper from, x6i 

Cushetunk trap, 122 

Cutting, tests on stones by, 20 



D. 



Dana, J. D.> cited 105 

DeCamp mine (see Hibernia). 

DeGraves Bros., test of stone from,.. 54 

Dell mine (see Scrub Oak) 176 

Diabase, tests on, 28, 50, 52 

Diamond drilling, cost of 8 

Dickerson mine, 175, 176 

Dover, test on stone from 40 



E. 



East Livingston, well near iii 

Edison Portland Cement Company, 

white limestone of, 177 

Elizabeth mine 176 

Employees on Survey, 3 



13 GEOL 



(189) 



igo 



INDEX. 



F. 

Page 

Fanning, Thos., test of stone from, ... 40 

Faults in Triassic, 127 

age of, 129 

overthrusts, 15 

Federal Hill Granite Company, test of 

stone from, 38 

Feltville, 151 

Ferguson, W. A., trap rock tests, 171 

Ferric oxide, leaching out of, 162 

Fire tests on building stones, 33 

methods of making az 

First Mountain, origin of flow, 124 

Flemington copper mine 144. X45 

Fort Lee, copper near, 155 

Francisco Bros., trap tests, 171 

Franklin Furnace, test of stone from,. 70 

French copper mine, 151 

Fresh Ponds, wells at, 1x9 

Q. 

Gage, R. B., 12, 79 

Gamble & Son, tests of stone from,... 68 

Geological collections, 6 

German Valley, test of stone from 3* 

Glass sand, amount produced, 9^ 

analyses of, 90, 92* 93 

areas of, 80 

cost of, 94 

chemical composition, 89 

description of deposits, ... 82 

effect of iron in 9^ 

elimination of iron, 9^ 

impurities in, 89 

industry, condition of, 79 

methods of mining 84 

mineral composition 91 

prices of, 80 

producers of, 95 

report on, la 

shape of grains 86 

size of grains, 87 

table of sixes, 88 

washing, 85 

whiteness of, 9* 

Glen Ridge, copper at, iS4 

Gneisses, tests on, 23, 

36, 34. 36, 40, 4a. 46, 48 

Gold at Arlington copper mine, i43 

Granite-gneiss, tests of 38 

Granites, tests of, «6 

Gr»nton trap ^** 

Griggstown copper mine 136-139 

H. 

Haelig, Wm., trap rock tests 172 

Hardness of road metal, 166 

trap rock, 171 



Page 

Hartshorn, Stewart, trap rock tests,... 172 

Hibemia mines, 176 

Hibemia, test of stone from, 46 

Hoffman copper mine, 250 

Hoff mine, 175, 176 

Hook Mountain 109 

Hosier, Helmer, trap rock tests 171 

Hude mine 175, 176 

Hudson river, fault along, 128 

Hunt, N. H., white limestone of, 177 

Hurd mine, 176 

Hydrocuprite, 247 

Hydrothermal origin of copper ores,.. x6o 

I. 

Ilmenite in glass sand ; '89, 91, 95 

Intrusive trap sheets, origin of, 125 

origin of copper 

ores in, x6o 

Iron, effects of, in glass sand 92 

mines, list of active X75 

report on za 

ore, production of, 175, 179 

J. 

Jamesburg, glass sand near, 8x 

Jenny Jump Mountain, X5 

Jersey City Water Supply Company, 

test of stone from 36 

K. 

Kice, Lyman, test of stone from, 32 

Knapp, G. N., X3 

Ktimmel, H. B., reports by x, 79, X73 



Lambertville, test of stone from,... 52, 171 

Lava flows, X13 

Lava, pressure of, 126 

Leonard shaft, . .*. 17^ 

Leucoxene in glass sand 89, 91 

Lewis, J. Volney xo, 97, 165 

Library, 6 

Liththipe & Son, trap rock tests, X71 

Limestone, 8 

industry I77 

test of, 24, 30, 70, 73, 74 

white, composition of, X78 

production of, i77 

uses of, X78 

Long Hill 109, X25 

Lubey, P., test of stone from 48 

M. 

Malachite, ^3Sf 

X36, X38, X42, 14s. X47. isx, 153 



INDEX. 



191 



Page 

Maps, new topographical 9 

sheets published, 4 

sheets sold 5 

Margerum Bros., tests of stone from,. 7& 

Marley, F. J., trap rock tests, 171 

Martinsville, copper near, 151 

test of stone from, 60 

Maurer station, wells at, 118 

Maurice river, glass sand near, 8z 

McCourt, W. E., 10, 17 

McKieman & Bergen, trap tests from,. 171 

Menlo Park copper mine, 153 

origin of ore at, 163 

Millington Crushed Stone Company, 

trap rock tests, 171 

Millville, glass sand near, 8z 

Mineral statistics, 179 

Mineral waters, 12 

Mining industry, 173 

Montville, tests of stone from, 36 

Morristown, tests of stone from, 48 

Mount Arlington, tests of stone from, 42 

Mount Gilboa, X20 

Mount Hope mines 176 

N. 

Nason, Frank t,-, 8 

Newark rocks, arid climate, 108 

character of, loi 

conditions of origin, ... 103 

deformation of, 127 

erosion of 127 

estuarine, origin of, ... J03 

extent of 99 

lake deposits 104 

origin of, 99 

Piedmont plain, origin 

of, Z06 

river origin of, 105 

sources of, loi 

thickness of, 107 

tilting of, 107 

New Brunswick, copper near, 151 

origin of ore at, .... 163 

trap near, 119 

New Germantown, trap near, 115 

New Jersey Lime Company, limestone, 177 
New Jersey Stone Company, tests of 

stone from, 34 

Newton, test of stone from, 72 

Newtown, copper near 155 

origin of copper near, 163 

silver near, 155 

New Vernon trap ridges, no 

Nicoll & Co., test of stone from, 70 

white limestone from, .. 177 

North Arlington, test of stone from, . . 66 
North Jersey Stone Co., test of stone 

from, 42, 44 



o. 

Page 
O'Donnell & McManniman, test of 

stone from, 72 

O'Neill & Hopkins, trap rock tests, ... 271 

O'Rourke, John, trap rock tests, 171 

Osborne & Marcellis, trap rock tests,.. 171 

P. 

Packanack Mountain 109 

Page, L. W., quoted, 166 

Paleobotany, work in, z6 

Paleontology, work in, 15 

Paleozoic work 14 

Palisades, 17 

Palisades, offshoots from, 121 

relations to shales, 120 

Panther Hill Granite Co., test of stone 

from, 34 

Parmelee, C. W., xo 

Paterson Crushed Stone Co., trap tests, 171 

Peat, report on, zo 

Pennington Mountain, copper on, Z55 

trap near, z20 

Perth Amboy, wells at, z z8 

Phillipsburg, test of stone from 74 

Plainfield, copper mine near, Z50 

origin of copper ore 162 

test of stone from, 50 

Pleasantdale, test of stone from 62 

Pleistocene work ' 23 

Pluckemin, copper mines near 250 

Pompton Junction, test of stone from, 38 

Potter, A. A., trap rock tests, 272 

Pressure of Newark sediments, 226 

Princeton, test of stone from 76 

Publications, 4, 283 

Pyroxene, copper in, 234 

R. 

Raritan mine, 2 52 

Raven Rock, test of stone from, ../... 58 

Reports, distribution of 6 

published, 4 

Richard mine, '276 

Riker Hill 109 

Road metal, qualities of, 266 

Rocky Hill, 227 

copper mine at, 236 

Round Mountain trap, 222 

Rutile in glass sand 89, 92 

8. 

St. Louis Exposition, medals from, .... 26 

Sand Brook trap sheet 225 

Sandstones, tests of, 

24, 29, 54, 56, 58, 60, 62, 64, 66, 68 

Schuyler mine, 240, 242, 243 

Scrub Oak mine, 276